Fitting Nonlinear Curves by use of Optimization Techniques
Hill, Scott A.
2005-01-01
MULTIVAR is a FORTRAN 77 computer program that fits one of the members of a set of six multivariable mathematical models (five of which are nonlinear) to a multivariable set of data. The inputs to MULTIVAR include the data for the independent and dependent variables plus the user s choice of one of the models, one of the three optimization engines, and convergence criteria. By use of the chosen optimization engine, MULTIVAR finds values for the parameters of the chosen model so as to minimize the sum of squares of the residuals. One of the optimization engines implements a routine, developed in 1982, that utilizes the Broydon-Fletcher-Goldfarb-Shanno (BFGS) variable-metric method for unconstrained minimization in conjunction with a one-dimensional search technique that finds the minimum of an unconstrained function by polynomial interpolation and extrapolation without first finding bounds on the solution. The second optimization engine is a faster and more robust commercially available code, denoted Design Optimization Tool, that also uses the BFGS method. The third optimization engine is a robust and relatively fast routine that implements the Levenberg-Marquardt algorithm.
Lmfit: Non-Linear Least-Square Minimization and Curve-Fitting for Python
Newville, Matthew; Stensitzki, Till; Allen, Daniel B.; Rawlik, Michal; Ingargiola, Antonino; Nelson, Andrew
2016-06-01
Lmfit provides a high-level interface to non-linear optimization and curve fitting problems for Python. Lmfit builds on and extends many of the optimization algorithm of scipy.optimize, especially the Levenberg-Marquardt method from optimize.leastsq. Its enhancements to optimization and data fitting problems include using Parameter objects instead of plain floats as variables, the ability to easily change fitting algorithms, and improved estimation of confidence intervals and curve-fitting with the Model class. Lmfit includes many pre-built models for common lineshapes.
On Fitting Nonlinear Latent Curve Models to Multiple Variables Measured Longitudinally
Blozis, Shelley A.
2007-01-01
This article shows how nonlinear latent curve models may be fitted for simultaneous analysis of multiple variables measured longitudinally using Mx statistical software. Longitudinal studies often involve observation of several variables across time with interest in the associations between change characteristics of different variables measured…
High-resolution fiber optic temperature sensors using nonlinear spectral curve fitting technique
Su, Z. H.; Gan, J.; Yu, Q. K.; Zhang, Q. H.; Liu, Z. H.; Bao, J. M.
2013-04-01
A generic new data processing method is developed to accurately calculate the absolute optical path difference of a low-finesse Fabry-Perot cavity from its broadband interference fringes. The method combines Fast Fourier Transformation with nonlinear curve fitting of the entire spectrum. Modular functions of LabVIEW are employed for fast implementation of the data processing algorithm. The advantages of this technique are demonstrated through high performance fiber optic temperature sensors consisting of an infrared superluminescent diode and an infrared spectrometer. A high resolution of 0.01 °C is achieved over a large dynamic range from room temperature to 800 °C, limited only by the silica fiber used for the sensor.
Ph.H.B.F. Franses (Philip Hans)
1994-01-01
textabstractIn this paper, a simple Gompertz curve-fitting procedure is proposed. Its advantages include the facts that the stability of the saturation level over the sample period can be checked, and that no knowledge of its value is necessary for forecasting. An application to forecasting the stoc
Alves, Larissa A.; de Castro, Arthur H.; de Mendonça, Fernanda G.; de Mesquita, João P.
2016-05-01
The oxygenated functional groups present on the surface of carbon dots with an average size of 2.7 ± 0.5 nm were characterized by a variety of techniques. In particular, we discussed the fit data of potentiometric titration curves using a nonlinear regression method based on the Levenberg-Marquardt algorithm. The results obtained by statistical treatment of the titration curve data showed that the best fit was obtained considering the presence of five Brønsted-Lowry acids on the surface of the carbon dots with constant ionization characteristics of carboxylic acids, cyclic ester, phenolic and pyrone-like groups. The total number of oxygenated acid groups obtained was 5 mmol g-1, with approximately 65% (∼2.9 mmol g-1) originating from groups with pKa < 6. The methodology showed good reproducibility and stability with standard deviations below 5%. The nature of the groups was independent of small variations in experimental conditions, i.e. the mass of carbon dots titrated and initial concentration of HCl solution. Finally, we believe that the methodology used here, together with other characterization techniques, is a simple, fast and powerful tool to characterize the complex acid-base properties of these so interesting and intriguing nanoparticles.
Sze, K. H.; Barsukov, I. L.; Roberts, G. C. K.
A procedure for quantitative evaluation of cross-peak volumes in spectra of any order of dimensions is described; this is based on a generalized algorithm for combining appropriate one-dimensional integrals obtained by nonlinear-least-squares curve-fitting techniques. This procedure is embodied in a program, NDVOL, which has three modes of operation: a fully automatic mode, a manual mode for interactive selection of fitting parameters, and a fast reintegration mode. The procedures used in the NDVOL program to obtain accurate volumes for overlapping cross peaks are illustrated using various simulated overlapping cross-peak patterns. The precision and accuracy of the estimates of cross-peak volumes obtained by application of the program to these simulated cross peaks and to a back-calculated 2D NOESY spectrum of dihydrofolate reductase are presented. Examples are shown of the use of the program with real 2D and 3D data. It is shown that the program is able to provide excellent estimates of volume even for seriously overlapping cross peaks with minimal intervention by the user.
AKLSQF - LEAST SQUARES CURVE FITTING
Kantak, A. V.
1994-01-01
The Least Squares Curve Fitting program, AKLSQF, computes the polynomial which will least square fit uniformly spaced data easily and efficiently. The program allows the user to specify the tolerable least squares error in the fitting or allows the user to specify the polynomial degree. In both cases AKLSQF returns the polynomial and the actual least squares fit error incurred in the operation. The data may be supplied to the routine either by direct keyboard entry or via a file. AKLSQF produces the least squares polynomial in two steps. First, the data points are least squares fitted using the orthogonal factorial polynomials. The result is then reduced to a regular polynomial using Sterling numbers of the first kind. If an error tolerance is specified, the program starts with a polynomial of degree 1 and computes the least squares fit error. The degree of the polynomial used for fitting is then increased successively until the error criterion specified by the user is met. At every step the polynomial as well as the least squares fitting error is printed to the screen. In general, the program can produce a curve fitting up to a 100 degree polynomial. All computations in the program are carried out under Double Precision format for real numbers and under long integer format for integers to provide the maximum accuracy possible. AKLSQF was written for an IBM PC X/AT or compatible using Microsoft's Quick Basic compiler. It has been implemented under DOS 3.2.1 using 23K of RAM. AKLSQF was developed in 1989.
Energy Technology Data Exchange (ETDEWEB)
Watson, C. R.; Cochran, M. I.; Thomas, J. M.; Eberhardt, L. L
1977-11-01
To find a mathematical model which describes (fits) data from a process which is fundamentally nonlinear, one usually uses nonlinear least-squares techniques on maxicomputers. These usually run in batch mode with the user supplying a model and initial ''guesstimates'' of its parameters. However, fitting the model to the data can be considered an art because computer algorithms either converge to true solutions, or converge to erroneous solutions, or fail to converge, depending on the quality of the guesstimates. It is slow and expensive to try enough runs to obtain a logical solution (unless one makes lucky initial guesses). An interactive BASIC procedure was developed which runs on either the PDP-11/34 under RT-11 or the PDP-11/70 under IAS. These programs help the investigator quickly fit the model to the data and statistically evaluate the differences between the two. The parameter estimates thus determined may then be used as guesstimates for the more precise maxicomputer codes. The key to the system is the re-enterant nature of the curve fitting routine (allowed only with a language such as INTERPRETED BASIC). The user supplies estimates of the parameters for the selected model (18 are currently available, and users can easily write their own). The computer tries a few iterative refinements (by using Taylor series expansion of partial derivatives to obtain linearization) of the estimates in an attempt to minimize the deviations between the values predicted by the model and the observed data. The user can observe as the program executes whether the result is a logical solution. If not, he may stop the process, enter new guesstimates, and examine those results, try again, or select a new model.
Space curves, anholonomy and nonlinearity
Indian Academy of Sciences (India)
Radha Balakrishnan
2005-04-01
Using classical differential geometry, we discuss the phenomenon of anholonomy that gets associated with a static and a moving curve. We obtain the expressions for the respective geometric phases in the two cases and interpret them. We show that there is a close connection between anholonomy and nonlinearity in a wide class of nonlinear systems.
Interpolation and Polynomial Curve Fitting
Yang, Yajun; Gordon, Sheldon P.
2014-01-01
Two points determine a line. Three noncollinear points determine a quadratic function. Four points that do not lie on a lower-degree polynomial curve determine a cubic function. In general, n + 1 points uniquely determine a polynomial of degree n, presuming that they do not fall onto a polynomial of lower degree. The process of finding such a…
Bounded Population Growth: A Curve Fitting Lesson.
Mathews, John H.
1992-01-01
Presents two mathematical methods for fitting the logistic curve to population data supplied by the U.S. Census Bureau utilizing computer algebra software to carry out the computations and plot graphs. (JKK)
Least-squares fitting Gompertz curve
Jukic, Dragan; Kralik, Gordana; Scitovski, Rudolf
2004-08-01
In this paper we consider the least-squares (LS) fitting of the Gompertz curve to the given nonconstant data (pi,ti,yi), i=1,...,m, m≥3. We give necessary and sufficient conditions which guarantee the existence of the LS estimate, suggest a choice of a good initial approximation and give some numerical examples.
Modeling and Fitting Exoplanet Transit Light Curves
Millholland, Sarah; Ruch, G. T.
2013-01-01
We present a numerical model along with an original fitting routine for the analysis of transiting extra-solar planet light curves. Our light curve model is unique in several ways from other available transit models, such as the analytic eclipse formulae of Mandel & Agol (2002) and Giménez (2006), the modified Eclipsing Binary Orbit Program (EBOP) model implemented in Southworth’s JKTEBOP code (Popper & Etzel 1981; Southworth et al. 2004), or the transit model developed as a part of the EXOFAST fitting suite (Eastman et al. in prep.). Our model employs Keplerian orbital dynamics about the system’s center of mass to properly account for stellar wobble and orbital eccentricity, uses a unique analytic solution derived from Kepler’s Second Law to calculate the projected distance between the centers of the star and planet, and calculates the effect of limb darkening using a simple technique that is different from the commonly used eclipse formulae. We have also devised a unique Monte Carlo style optimization routine for fitting the light curve model to observed transits. We demonstrate that, while the effect of stellar wobble on transit light curves is generally small, it becomes significant as the planet to stellar mass ratio increases and the semi-major axes of the orbits decrease. We also illustrate the appreciable effects of orbital ellipticity on the light curve and the necessity of accounting for its impacts for accurate modeling. We show that our simple limb darkening calculations are as accurate as the analytic equations of Mandel & Agol (2002). Although our Monte Carlo fitting algorithm is not as mathematically rigorous as the Markov Chain Monte Carlo based algorithms most often used to determine exoplanetary system parameters, we show that it is straightforward and returns reliable results. Finally, we show that analyses performed with our model and optimization routine compare favorably with exoplanet characterizations published by groups such as the
Multivariate curve-fitting in GAUSS
Bunck, C.M.; Pendleton, G.W.
1988-01-01
Multivariate curve-fitting techniques for repeated measures have been developed and an interactive program has been written in GAUSS. The program implements not only the one-factor design described in Morrison (1967) but also includes pairwise comparisons of curves and rates, a two-factor design, and other options. Strategies for selecting the appropriate degree for the polynomial are provided. The methods and program are illustrated with data from studies of the effects of environmental contaminants on ducklings, nesting kestrels and quail.
Nonlinear fitness landscape of a molecular pathway.
Directory of Open Access Journals (Sweden)
Lilia Perfeito
2011-07-01
Full Text Available Genes are regulated because their expression involves a fitness cost to the organism. The production of proteins by transcription and translation is a well-known cost factor, but the enzymatic activity of the proteins produced can also reduce fitness, depending on the internal state and the environment of the cell. Here, we map the fitness costs of a key metabolic network, the lactose utilization pathway in Escherichia coli. We measure the growth of several regulatory lac operon mutants in different environments inducing expression of the lac genes. We find a strikingly nonlinear fitness landscape, which depends on the production rate and on the activity rate of the lac proteins. A simple fitness model of the lac pathway, based on elementary biophysical processes, predicts the growth rate of all observed strains. The nonlinearity of fitness is explained by a feedback loop: production and activity of the lac proteins reduce growth, but growth also affects the density of these molecules. This nonlinearity has important consequences for molecular function and evolution. It generates a cliff in the fitness landscape, beyond which populations cannot maintain growth. In viable populations, there is an expression barrier of the lac genes, which cannot be exceeded in any stationary growth process. Furthermore, the nonlinearity determines how the fitness of operon mutants depends on the inducer environment. We argue that fitness nonlinearities, expression barriers, and gene-environment interactions are generic features of fitness landscapes for metabolic pathways, and we discuss their implications for the evolution of regulation.
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…
Energy Technology Data Exchange (ETDEWEB)
Torello, David [GW Woodruff School of Mechanical Engineering, Georgia Tech (United States); Kim, Jin-Yeon [School of Civil and Environmental Engineering, Georgia Tech (United States); Qu, Jianmin [Department of Civil and Environmental Engineering, Northwestern University (United States); Jacobs, Laurence J. [School of Civil and Environmental Engineering, Georgia Tech and GW Woodruff School of Mechanical Engineering, Georgia Tech (United States)
2015-03-31
This research considers the effects of diffraction, attenuation, and the nonlinearity of generating sources on measurements of nonlinear ultrasonic Rayleigh wave propagation. A new theoretical framework for correcting measurements made with air-coupled and contact piezoelectric receivers for the aforementioned effects is provided based on analytical models and experimental considerations. A method for extracting the nonlinearity parameter β{sub 11} is proposed based on a nonlinear least squares curve-fitting algorithm that is tailored for Rayleigh wave measurements. Quantitative experiments are conducted to confirm the predictions for the nonlinearity of the piezoelectric source and to demonstrate the effectiveness of the curve-fitting procedure. These experiments are conducted on aluminum 2024 and 7075 specimens and a β{sub 11}{sup 7075}/β{sub 11}{sup 2024} measure of 1.363 agrees well with previous literature and earlier work.
Geometrodynamics: The Nonlinear Dynamics of Curved Spacetime
Scheel, Mark A.; Thorne, Kip S.
2017-01-01
We review discoveries in the nonlinear dynamics of curved spacetime, largely made possible by numerical solutions of Einstein's equations. We discuss critical phenomena and self-similarity in gravitational collapse, the behavior of spacetime curvature near singularities, the instability of black strings in 5 spacetime dimensions, and the collision of four-dimensional black holes. We also discuss the prospects for further discoveries in geometrodynamics via observation of gravitational waves.
McCraig, Michael A.; Osinski, Gordon R.; Cloutis, Edward A.; Flemming, Roberta L.; Izawa, Matthew R. M.; Reddy, Vishnu; Fieber-Beyer, Sherry K.; Pompilio, Loredana; van der Meer, Freek; Berger, Jeffrey A.; Bramble, Michael S.; Applin, Daniel M.
2017-03-01
Spectroscopy in planetary science often provides the only information regarding the compositional and mineralogical make up of planetary surfaces. The methods employed when curve fitting and modelling spectra can be confusing and difficult to visualize and comprehend. Researchers who are new to working with spectra may find inadequate help or documentation in the scientific literature or in the software packages available for curve fitting. This problem also extends to the parameterization of spectra and the dissemination of derived metrics. Often, when derived metrics are reported, such as band centres, the discussion of exactly how the metrics were derived, or if there was any systematic curve fitting performed, is not included. Herein we provide both recommendations and methods for curve fitting and explanations of the terms and methods used. Techniques to curve fit spectral data of various types are demonstrated using simple-to-understand mathematics and equations written to be used in Microsoft Excel® software, free of macros, in a cut-and-paste fashion that allows one to curve fit spectra in a reasonably user-friendly manner. The procedures use empirical curve fitting, include visualizations, and ameliorates many of the unknowns one may encounter when using black-box commercial software. The provided framework is a comprehensive record of the curve fitting parameters used, the derived metrics, and is intended to be an example of a format for dissemination when curve fitting data.
Curve fitting methods for solar radiation data modeling
Energy Technology Data Exchange (ETDEWEB)
Karim, Samsul Ariffin Abdul, E-mail: samsul-ariffin@petronas.com.my, E-mail: balbir@petronas.com.my; Singh, Balbir Singh Mahinder, E-mail: samsul-ariffin@petronas.com.my, E-mail: balbir@petronas.com.my [Department of Fundamental and Applied Sciences, Faculty of Sciences and Information Technology, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia)
2014-10-24
This paper studies the use of several type of curve fitting method to smooth the global solar radiation data. After the data have been fitted by using curve fitting method, the mathematical model of global solar radiation will be developed. The error measurement was calculated by using goodness-fit statistics such as root mean square error (RMSE) and the value of R{sup 2}. The best fitting methods will be used as a starting point for the construction of mathematical modeling of solar radiation received in Universiti Teknologi PETRONAS (UTP) Malaysia. Numerical results indicated that Gaussian fitting and sine fitting (both with two terms) gives better results as compare with the other fitting methods.
Curve fitting methods for solar radiation data modeling
Karim, Samsul Ariffin Abdul; Singh, Balbir Singh Mahinder
2014-10-01
This paper studies the use of several type of curve fitting method to smooth the global solar radiation data. After the data have been fitted by using curve fitting method, the mathematical model of global solar radiation will be developed. The error measurement was calculated by using goodness-fit statistics such as root mean square error (RMSE) and the value of R2. The best fitting methods will be used as a starting point for the construction of mathematical modeling of solar radiation received in Universiti Teknologi PETRONAS (UTP) Malaysia. Numerical results indicated that Gaussian fitting and sine fitting (both with two terms) gives better results as compare with the other fitting methods.
Real-Time Exponential Curve Fits Using Discrete Calculus
Rowe, Geoffrey
2010-01-01
An improved solution for curve fitting data to an exponential equation (y = Ae(exp Bt) + C) has been developed. This improvement is in four areas -- speed, stability, determinant processing time, and the removal of limits. The solution presented avoids iterative techniques and their stability errors by using three mathematical ideas: discrete calculus, a special relationship (be tween exponential curves and the Mean Value Theorem for Derivatives), and a simple linear curve fit algorithm. This method can also be applied to fitting data to the general power law equation y = Ax(exp B) + C and the general geometric growth equation y = Ak(exp Bt) + C.
Comparison of ductile-to-brittle transition curve fitting approaches
Energy Technology Data Exchange (ETDEWEB)
Cao, L.W. [School of Materials Science and Engineering, Beihang University (BUAA), Beijing 100191 (China)] [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Wu, S.J., E-mail: wusj@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), Beijing 100191 (China); Flewitt, P.E.J. [Interface Analysis Centre, University of Bristol, Bristol BS2 8BS (United Kingdom)] [School of Physics, HH Wills Laboratory, University of Bristol, BS8 1TL (United Kingdom)
2012-05-15
Ductile-to-brittle transition (DBT) curve fitting approaches are compared over the transition temperature range for reactor pressure vessel steels with different kinds of data, including Charpy-V notch impact energy data and fracture toughness data. Three DBT curve fitting methods have been frequently used in the past, including the Burr S-Weibull and tanh distributions. In general there is greater scatter associated with test data obtained within the transition region. Therefore these methods give results with different accuracies, especially when fitting to small quantities of data. The comparison shows that the Burr distribution and tanh distribution can almost equally fit well distributed and large data sets extending across the test temperature range to include the upper and lower shelves. The S-Weibull distribution fit is poor for the lower shelf of the DBT curve. Overall for both large and small quantities of measured data the Burr distribution provides the best description. - Highlights: Black-Right-Pointing-Pointer Burr distribution offers a better fit than that of a S-Weibull and tanh fit. Black-Right-Pointing-Pointer Burr and tanh methods show similar fitting ability for a large data set. Black-Right-Pointing-Pointer Burr method can fit sparse data well distributed across the test temperature. Black-Right-Pointing-Pointer S-Weibull method cannot fit the lower shelf well and show poor fitting quality.
Mössbauer spectral curve fitting combining fundamentally different techniques
Susanto, Ferry; de Souza, Paulo
2016-10-01
We propose the use of fundamentally distinctive techniques to solve the problem of curve fitting a Mössbauer spectrum. The techniques we investigated are: evolutionary algorithm, basin hopping, and hill climbing. These techniques were applied in isolation and combined to fit different shapes of Mössbauer spectra. The results indicate that complex Mössbauer spectra can be automatically curve fitted using minimum user input, and combination of these techniques achieved the best performance (lowest statistical error). The software and sample of Mössbauer spectra have been made available through a link at the reference.
Mössbauer spectral curve fitting combining fundamentally different techniques
Energy Technology Data Exchange (ETDEWEB)
Susanto, Ferry [School of Engineering and ICT, University of Tasmania, Sandy Bay, TAS 7005 (Australia); College of Engineering and Science, Victoria University, Footscray, VIC 3011 (Australia); Data61, CSIRO, College Road, Sandy Bay, TAS 7005 (Australia); Souza, Paulo de [School of Engineering and ICT, University of Tasmania, Sandy Bay, TAS 7005 (Australia); Data61, CSIRO, College Road, Sandy Bay, TAS 7005 (Australia)
2016-10-15
We propose the use of fundamentally distinctive techniques to solve the problem of curve fitting a Mössbauer spectrum. The techniques we investigated are: evolutionary algorithm, basin hopping, and hill climbing. These techniques were applied in isolation and combined to fit different shapes of Mössbauer spectra. The results indicate that complex Mössbauer spectra can be automatically curve fitted using minimum user input, and combination of these techniques achieved the best performance (lowest statistical error). The software and sample of Mössbauer spectra have been made available through a link at the reference.
New method of best-fitting on curved surface
Kyusojin, Akira; Akimoto, Yoshinori
1993-09-01
With the coordinates measuring machine the measured points are obtained as a series of points consist of the original feature and the deviations caused by misalignment i. e. translated deviation and angular deviation. To evaluate the form deviation accurately it is required to best-fit the measured feature to the ideal feature. Conventional best-fitting has been done to minimize the sum of squares of deviations between measured feature and ideal feature by translating and rotating the measured feature. It is possible for the curved line but too difficult for the curved surface. This paper gives a new method of best-fitting using datums which minimize the sum of squares in its normal direction. The datum is defined as straight line for the curved line and plane for the curved surface. When the datum of measured feature is coincided with that of the ideal feature the deviations caused by misslignment are eliminated. In order to confirm the reliability of this method computer simulations and practical measurements were made. Then close agreement was obtained. Key words: coordinate measuring machine best-fitting curved surface datum method of least-squares form deviation software on the measurement accuracy y C) - Measured feature . /Ideal feature -I. Fig. 1 Conventional bestfitting method Ideal Measured feature feature eviation a) curved line Fig. 2 Designation of form deviation 54 / SPIE Vol. 2101 Measurement Technology and Intelligent Instruments (1993) b) curved surface
Viscosity Coefficient Curve Fits for Ionized Gas Species Grant Palmer
Palmer, Grant; Arnold, James O. (Technical Monitor)
2001-01-01
Viscosity coefficient curve fits for neutral gas species are available from many sources. Many do a good job of reproducing experimental and computational chemistry data. The curve fits are usually expressed as a function of temperature only. This is consistent with the governing equations used to derive an expression for the neutral species viscosity coefficient. Ionized species pose a more complicated problem. They are subject to electrostatic as well as intermolecular forces. The electrostatic forces are affected by a shielding phenomenon where electrons shield the electrostatic forces of positively charged ions beyond a certain distance. The viscosity coefficient for an ionized gas species is a function of both temperature and local electron number density. Currently available curve fits for ionized gas species, such as those presented by Gupta/Yos, are a function of temperature only. What they did was to assume an electron number density. The problem is that the electron number density they assumed was unrealistically high. The purpose of this paper is two-fold. First, the proper expression for determining the viscosity coefficient of an ionized species as a function of both temperature and electron number density will be presented. Then curve fit coefficients will be developed using the more realistic assumption of an equilibrium electron number density. The results will be compared against previous curve fits and against highly accurate computational chemistry data.
Curve Fitting And Interpolation Model Applied In Nonel Dosage Detection
Directory of Open Access Journals (Sweden)
Jiuling Li
2013-06-01
Full Text Available The Curve Fitting and Interpolation Model are applied in Nonel dosage detection in this paper firstly, and the gray of continuous explosive in the Nonel has been forecasted. Although the traditional infrared equipment establishes the relationship of explosive dosage and light intensity, but the forecast accuracy is very low. Therefore, gray prediction models based on curve fitting and interpolation are framed separately, and the deviations from the different models are compared. Simultaneously, combining on the sample library features, the cubic polynomial fitting curve of the higher precision is used to predict grays, and 5mg-28mg Nonel gray values are calculated by MATLAB. Through the predictive values, the dosage detection operations are simplified, and the defect missing rate of the Nonel are reduced. Finally, the quality of Nonel is improved.
Non-linear Least Squares Fitting in IDL with MPFIT
Markwardt, Craig B
2009-01-01
MPFIT is a port to IDL of the non-linear least squares fitting program MINPACK-1. MPFIT inherits the robustness of the original FORTRAN version of MINPACK-1, but is optimized for performance and convenience in IDL. In addition to the main fitting engine, MPFIT, several specialized functions are provided to fit 1-D curves and 2-D images; 1-D and 2-D peaks; and interactive fitting from the IDL command line. Several constraints can be applied to model parameters, including fixed constraints, simple bounding constraints, and "tying" the value to another parameter. Several data weighting methods are allowed, and the parameter covariance matrix is computed. Extensive diagnostic capabilities are available during the fit, via a call-back subroutine, and after the fit is complete. Several different forms of documentation are provided, including a tutorial, reference pages, and frequently asked questions. The package has been translated to C and Python as well. The full IDL and C packages can be found at http://purl.co...
Neutron Multiplicity: LANL W Covariance Matrix for Curve Fitting
Energy Technology Data Exchange (ETDEWEB)
Wendelberger, James G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-12-08
In neutron multiplicity counting one may fit a curve by minimizing an objective function, χ$2\\atop{n}$. The objective function includes the inverse of an n by n matrix of covariances, W. The inverse of the W matrix has a closed form solution. In addition W^{-1} is a tri-diagonal matrix. The closed form and tridiagonal nature allows for a simpler expression of the objective function χ$2\\atop{n}$. Minimization of this simpler expression will provide the optimal parameters for the fitted curve.
Quantifying and Reducing Curve-Fitting Uncertainty in Isc: Preprint
Energy Technology Data Exchange (ETDEWEB)
Campanelli, Mark; Duck, Benjamin; Emery, Keith
2015-09-28
Current-voltage (I-V) curve measurements of photovoltaic (PV) devices are used to determine performance parameters and to establish traceable calibration chains. Measurement standards specify localized curve fitting methods, e.g., straight-line interpolation/extrapolation of the I-V curve points near short-circuit current, Isc. By considering such fits as statistical linear regressions, uncertainties in the performance parameters are readily quantified. However, the legitimacy of such a computed uncertainty requires that the model be a valid (local) representation of the I-V curve and that the noise be sufficiently well characterized. Using more data points often has the advantage of lowering the uncertainty. However, more data points can make the uncertainty in the fit arbitrarily small, and this fit uncertainty misses the dominant residual uncertainty due to so-called model discrepancy. Using objective Bayesian linear regression for straight-line fits for Isc, we investigate an evidence-based method to automatically choose data windows of I-V points with reduced model discrepancy. We also investigate noise effects. Uncertainties, aligned with the Guide to the Expression of Uncertainty in Measurement (GUM), are quantified throughout.
How Graphing Calculators Find Curves of Best Fit
Shore, Mark; Shore, JoAnna; Boggs, Stacey
2004-01-01
For over a decade mathematics instructors have been using graphing calculators in courses ranging from developmental mathematics (Beginning and Intermediate Algebra) to Calculus and Statistics. One of the key functions that make them so powerful in the teaching and learning process is their ability to find curves of best fit. Instructors may use…
A New Curve Fitting Method for Forming Limit Experimental Data
Institute of Scientific and Technical Information of China (English)
Jieshi CHEN; Xianbin ZHOU
2005-01-01
The forming limit curve (FLC) can be obtained by. means of curve fitting the limit strain points of different strain paths. The theory of percent regression analysis is applied to the curve fitting of forming limit experimental data.Forecast intervals of FLC percentiles can be calculated. Thus reliability and confidence level can be considered. The theoretical method to get the limits of limit strain points distributing region is presented, and the FLC position can be adjusted according to practical requirement. Method for establishing FLC with high reliability using small samples is presented at the same time. This method can make full use of the current experimental data and the previous data.Compared with the traditional method that can only use current experimental data, fewer specimens are required in the present method to obtain the same precision and the result is more accurate with the same number of specimens.
Focusing of light through turbid media by curve fitting optimization
Gong, Changmei; Wu, Tengfei; Liu, Jietao; Li, Huijuan; Shao, Xiaopeng; Zhang, Jianqi
2016-12-01
The construction of wavefront phase plays a critical role in focusing light through turbid media. We introduce the curve fitting algorithm (CFA) into the feedback control procedure for wavefront optimization. Unlike the existing continuous sequential algorithm (CSA), the CFA locates the optimal phase by fitting a curve to the measured signals. Simulation results show that, similar to the genetic algorithm (GA), the proposed CFA technique is far less susceptible to the experimental noise than the CSA. Furthermore, only three measurements of feedback signals are enough for CFA to fit the optimal phase while obtaining a higher focal intensity than the CSA and the GA, dramatically shortening the optimization time by a factor of 3 compared with the CSA and the GA. The proposed CFA approach can be applied to enhance the focus intensity and boost the focusing speed in the fields of biological imaging, particle trapping, laser therapy, and so on, and might help to focus light through dynamic turbid media.
McCraig, M.A.; Osinski, G.R.; Cloutis, E.A.; Flemming, R.L.; Izawa, M.R.M.; Reddy, V.; Fieber-Beyer, S.K.; Pompilio, L.; van der Meer, F.D.; Berger, J.A.; Bramble, M.S.; Applin, D.M.
2017-01-01
Spectroscopy in planetary science often provides the only information regarding the compositional and mineralogical make up of planetary surfaces. The methods employed when curve fitting and modelling spectra can be confusing and difficult to visualize and comprehend. Researchers who are new to
Identification of systems containing nonlinear stiffnesses using backbone curves
Londoño, Julián M.; Cooper, Jonathan E.; Neild, Simon A.
2017-02-01
This paper presents a method for the dynamic identification of structures containing discrete nonlinear stiffnesses. The approach requires the structure to be excited at a single resonant frequency, enabling measurements to be made in regimes of large displacements where nonlinearities are more likely to be significant. Measured resonant decay data is used to estimate the system backbone curves. Linear natural frequencies and nonlinear parameters are identified using these backbone curves assuming a form for the nonlinear behaviour. Numerical and experimental examples, inspired by an aerospace industry test case study, are considered to illustrate how the method can be applied. Results from these models demonstrate that the method can successfully deliver nonlinear models able to predict the response of the test structure nonlinear dynamics.
Localization of nonlinear excitations in curved waveguides
DEFF Research Database (Denmark)
Gaididei, Yu. B.; Christiansen, Peter Leth; Kevrekidis, P. G.;
2005-01-01
numerical simulations of the nonlinear problem and in this case localized excitations are found to persist. We found also interesting relaxational dynamics. Analogies of the present problem in context related to atomic physics and particularly to Bose–Einstein condensation are discussed....
3D CATENARY CURVE FITTING FOR GEOMETRIC CALIBRATION
Directory of Open Access Journals (Sweden)
T.-O. Chan
2012-09-01
Full Text Available In modern road surveys, hanging power cables are among the most commonly-found geometric features. These cables are catenary curves that are conventionally modelled with three parameters in 2D Cartesian space. With the advent and popularity of the mobile mapping system (MMS, the 3D point clouds of hanging power cables can be captured within a short period of time. These point clouds, similarly to those of planar features, can be used for feature-based self-calibration of the system assembly errors of an MMS. However, to achieve this, a well-defined 3D equation for the catenary curve is needed. This paper proposes three 3D catenary curve models, each having different parameters. The models are examined by least squares fitting of simulated data and real data captured with an MMS. The outcome of the fitting is investigated in terms of the residuals and correlation matrices. Among the proposed models, one of them could estimate the parameters accurately and without any extreme correlation between the variables. This model can also be applied to those transmission lines captured by airborne laser scanning or any other hanging cable-like objects.
Curve registration by nonparametric goodness-of-fit testing
Dalalyan, Arnak
2011-01-01
The problem of curve registration appears in many different areas of applications ranging from neuroscience to road traffic modeling. In the present work, we propose a nonparametric testing framework in which we develop a generalized likelihood ratio test to perform curve registration. We first prove that, under the null hypothesis, the resulting test statistic is asymptotically distributed as a chi-squared random variable. This result, often referred to as Wilks' phenomenon, provides a natural threshold for the test of a prescribed asymptotic significance level and a natural measure of lack-of-fit in terms of the p-value of the chi squared test. We also prove that the proposed test is consistent, i.e., its power is asymptotically equal to 1. Some numerical experiments on synthetic datasets are reported as well.
Deteksi Iris Berdasarkan Metode Black Hole dan Circle Curve Fitting
Directory of Open Access Journals (Sweden)
Danny Kurnianto
2013-11-01
Full Text Available Sistem pengenalan identitas personal berdasarkan ciri biometrika adalah suatu sistem pengenalan seseorang berdasarkan pada ciri biometrika yang melekat pada orang tersebut. Iris mata merupakan salah satu ciri biometrik yang handal untuk sistem pengenalan identitas personal. Bagian sistem pengenalan identitas personal berdasarkan biometrik iris yang dianggap paling krusial adalah deteksi lokasi iris, karena akurasi deteksi iris berpengaruh pada tingkat akurasi sistem secara keseluruhan. Lokasi iris pada citra mata dibatasi oleh dua buah lingkaran yang memisahkan antara bagian iris dengan pupil dan sklera. Telah banyak metodemetode yang diusulkan oleh para peneliti untuk menghasilkan deteksi lokasi iris dengan akurat dan cepat. Masalah akurasi, kecepatan waktu eksekusi dan ketahanan terhadap noise merupakan bidang penelitian yang menantang pada deteksi iris. Makalah ini menyajikan metode deteksi iris menggunakan metode black hole dan circle curve fitting. Langkah pertama, mencari batas dalam lingkaran iris yang memisahkan antara daerah iris dan pupil. Dengan metode black hole yang bekerja berdasarkan fakta bahwa lokasi pupil merupakan daerah lingkaran yang paling hitam dan memiliki distribusi nilai intensitas yang seragam, maka lokasi pupil dapat ditentukan dengan teknik pengambangan. Batas lingkaran pupil dapat ditentukan dengan circle curve fitting dari parameter lingkaran daerah pupil. Langkah kedua, mencari batas luar lingkaran iris yang memisahkan antara iris dan sklera. Peta tepi citra iris dicari dengan menggunakan deteksi tepi Canny, kemudian diambil satu komponen tepi arah vertikal yang dapat mewakili batas lingkaran luar iris. Dari komponen tepi tersebut, dihitung jari-jari iris yang berpusat di pusat pupil. Dengan jari-jari iris dan pusat iris maka dapat ditentukan batas luar iris menggunakan circle curve fitting
Spectral Curve Fitting for Automatic Hyperspectral Data Analysis
Brown, Adrian J
2014-01-01
Automatic discovery and curve fitting of absorption bands in hyperspectral data can enable the analyst to identify materials present in a scene by comparison with library spectra. This procedure is common in laboratory spectra, but is challenging for sparse hyperspectral data. A procedure for robust discovery of overlapping bands in hyperspectral data is described in this paper. The method is capable of automatically discovering and fitting symmetric absorption bands, can separate overlapping absorption bands in a stable manner, and has relatively low sensitivity to noise. A comparison with techniques already available in the literature is presented using simulated spectra. An application is demonstrated utilizing the shortwave infrared (2.0-2.5 micron or 5000-4000 cm-1) region. A small hyperspectral scene is processed to demonstrate the ability of the method to detect small shifts in absorption wavelength caused by varying white mica chemistry in a natural setting.
Liao, Fei; Tian, Kao-Cong; Yang, Xiao; Zhou, Qi-Xin; Zeng, Zhao-Chun; Zuo, Yu-Ping
2003-03-01
The reliability of kinetic substrate quantification by nonlinear fitting of the enzyme reaction curve to the integrated Michaelis-Menten equation was investigated by both simulation and preliminary experimentation. For simulation, product absorptivity epsilon was 3.00 mmol(-1) L cm(-1) and K(m) was 0.10 mmol L(-1), and uniform absorbance error sigma was randomly inserted into the error-free reaction curve of product absorbance A(i) versus reaction time t(i) calculated according to the integrated Michaelis-Menten equation. The experimental reaction curve of arylesterase acting on phenyl acetate was monitored by phenol absorbance at 270 nm. Maximal product absorbance A(m) was predicted by nonlinear fitting of the reaction curve to Eq. (1) with K(m) as constant. There were unique A(m) for best fitting of both the simulated and experimental reaction curves. Neither the error in reaction origin nor the variation of enzyme activity changed the background-corrected value of A(m). But the range of data under analysis, the background absorbance, and absorbance error sigma had an effect. By simulation, A(m) from 0.150 to 3.600 was predicted with reliability and linear response to substrate concentration when there was 80% consumption of substrate at sigma of 0.001. Restriction of absorbance to 0.700 enabled A(m) up to 1.800 to be predicted at sigma of 0.001. Detection limit reached A(m) of 0.090 at sigma of 0.001. By experimentation, the reproducibility was 4.6% at substrate concentration twice the K(m), and A(m) linearly responded to phenyl acetate with consistent absorptivity for phenol, and upper limit about twice the maximum of experimental absorbance. These results supported the reliability of this new kinetic method for enzymatic analysis with enhanced upper limit and precision.
Non-linear Behavior of Curved Sandwich Panels
DEFF Research Database (Denmark)
Berggreen, Carl Christian; Jolma, P.; Karjalainen, J. P.;
2003-01-01
In this paper the non-linear behavior of curved sandwich panels is investigated both numerically and experimentally. Focus is on various aspects of finite element modeling and calculation procedures. A simply supported, singly curved, CFRP/PVC sandwich panel is analyzed under uniform pressure load...... and results are compared to test data. A novel test arrangement utilizing a water filled cushion to create the uniform pressure load on curved panel specimen is used to obtain the experimental data. The panel is modeled with three different commercial finite element codes. Two implicit and one explicit code...... are used with various element types, modeling approaches and material models. The results show that the theoretical and experimental methods generally show fair agreement in panel non-linear behavior before collapse. It is also shown that special attention to detail has to be taken, because the predicted...
Directory of Open Access Journals (Sweden)
Andrés Iglesias
2016-01-01
Full Text Available Fitting curves to noisy data points is a difficult problem arising in many scientific and industrial domains. Although polynomial functions are usually applied to this task, there are many shapes that cannot be properly fitted by using this approach. In this paper, we tackle this issue by using rational Bézier curves. This is a very difficult problem that requires computing four different sets of unknowns (data parameters, poles, weights, and the curve degree strongly related to each other in a highly nonlinear way. This leads to a difficult continuous nonlinear optimization problem. In this paper, we propose two simulated annealing schemas (the all-in-one schema and the sequential schema to determine the data parameterization and the weights of the poles of the fitting curve. These schemas are combined with least-squares minimization and the Bayesian Information Criterion to calculate the poles and the optimal degree of the best fitting Bézier rational curve, respectively. We apply our methods to a benchmark of three carefully chosen examples of 2D and 3D noisy data points. Our experimental results show that this methodology (particularly, the sequential schema outperforms previous polynomial-based approaches for our data fitting problem, even in the presence of noise of low-medium intensity.
SHOWING THE THYRISTOR AND TRIAC HARMONICS IN 3D SPACE AND CURVE FITTING TO THD
Directory of Open Access Journals (Sweden)
Ahmet ALTINTAŞ
2004-03-01
Full Text Available The switching equipment, like thyristors and triacs, are widely used power electronics. Also, they have nonlinear load characteristics and produce effective harmonics. In order to compensate harmonic currents of nonlinear loads, THD value and the amplitude of harmonics produced from loads at the working conditions should be known. Also, this process is only possible with harmonic analysis. Harmonic analysis is expensive process because of demanding special equipment. In this study, by expressing harmonics, produced thyristor and triac with different load and firing angle, in 3D space, a new viewing point to show harmonic analysis was presented; with curve fitting to the THD values at the each firing angle, polynomials were obtained; by doing so, THD values will be directly found without harmonic analysis.
Fitting Higgs data with nonlinear effective theory
Energy Technology Data Exchange (ETDEWEB)
Buchalla, G.; Cata, O.; Celis, A.; Krause, C. [Ludwig-Maximilians-Universitaet Muenchen, Fakultaet fuer Physik Arnold Sommerfeld Center for Theoretical Physics, Muenchen (Germany)
2016-05-15
In a recent paper we showed that the electroweak chiral Lagrangian at leading order is equivalent to the conventional κ formalism used by ATLAS and CMS to test Higgs anomalous couplings. Here we apply this fact to fit the latest Higgs data. The new aspect of our analysis is a systematic interpretation of the fit parameters within an EFT. Concentrating on the processes of Higgs production and decay that have been measured so far, six parameters turn out to be relevant: c{sub V}, c{sub t}, c{sub b}, c{sub τ}, c{sub γγ}, c{sub gg}. A global Bayesian fit is then performed with the result c{sub V} = 0.98 ± 0.09, c{sub t} = 1.34 ± 0.19, c{sub b} = 0.78 ± 0.18, c{sub τ} = 0.92 ± 0.14, c{sub γγ} = -0.24 ± 0.37, c{sub gg} = -0.30 ± 0.17. Additionally, we show how this leading-order parametrization can be generalized to next-to-leading order, thus improving the κ formalism systematically. The differences with a linear EFT analysis including operators of dimension six are also discussed. One of the main conclusions of our analysis is that since the conventional κ formalism can be properly justified within a QFT framework, it should continue to play a central role in analyzing and interpreting Higgs data. (orig.)
Strategies for fitting nonlinear ecological models in R, AD Model Builder, and BUGS
Bolker, Benjamin M.; Gardner, Beth; Maunder, Mark; Berg, Casper W.; Brooks, Mollie; Comita, Liza; Crone, Elizabeth; Cubaynes, Sarah; Davies, Trevor; de Valpine, Perry; Ford, Jessica; Gimenez, Olivier; Kéry, Marc; Kim, Eun Jung; Lennert-Cody, Cleridy; Magunsson, Arni; Martell, Steve; Nash, John; Nielson, Anders; Regentz, Jim; Skaug, Hans; Zipkin, Elise
2013-01-01
1. Ecologists often use nonlinear fitting techniques to estimate the parameters of complex ecological models, with attendant frustration. This paper compares three open-source model fitting tools and discusses general strategies for defining and fitting models. 2. R is convenient and (relatively) easy to learn, AD Model Builder is fast and robust but comes with a steep learning curve, while BUGS provides the greatest flexibility at the price of speed. 3. Our model-fitting suggestions range from general cultural advice (where possible, use the tools and models that are most common in your subfield) to specific suggestions about how to change the mathematical description of models to make them more amenable to parameter estimation. 4. A companion web site (https://groups.nceas.ucsb.edu/nonlinear-modeling/projects) presents detailed examples of application of the three tools to a variety of typical ecological estimation problems; each example links both to a detailed project report and to full source code and data.
Classical black holes: the nonlinear dynamics of curved spacetime.
Thorne, Kip S
2012-08-03
Numerical simulations have revealed two types of physical structures, made from curved spacetime, that are attached to black holes: tendexes, which stretch or squeeze anything they encounter, and vortexes, which twist adjacent inertial frames relative to each other. When black holes collide, their tendexes and vortexes interact and oscillate (a form of nonlinear dynamics of curved spacetime). These oscillations generate gravitational waves, which can give kicks up to 4000 kilometers per second to the merged black hole. The gravitational waves encode details of the spacetime dynamics and will soon be observed and studied by the Laser Interferometer Gravitational Wave Observatory and its international partners.
ANALYTIC INVARIANT CURVES OF A NONLINEAR SECOND ORDER DIFFERENCE EQUATION
Institute of Scientific and Technical Information of China (English)
Wang Wusheng
2009-01-01
This article studies the existence of analytic invariant curves for a nonlinear second order difference equation which was modeled from macroeconomics of the business cycle. The author not only discusses the case of the eigenvalue off the unit circle S1 and the case on S1 with the Diophantine condition but also considers the case of the eigenvalue at a root of the unity, which obviously violates the Diophantine condition.
Dynamic modeling and analysis of vortex filament motion using a novel curve-fitting method
Directory of Open Access Journals (Sweden)
Chang-Joo Kim
2016-02-01
Full Text Available Applications of a novel curve-fitting technique are presented to efficiently predict the motion of the vortex filament, which is trailed from a rigid body such as wings and rotors. The governing equations of the motion, when a Lagrangian approach with the present curve-fitting method is applied, can be transformed into an easily solvable form of the system of nonlinear ordinary differential equations. The applicability of Bézier curves, B-spline, and Lagrange interpolating polynomials is investigated. Local Lagrange interpolating polynomials with a shift operator are proposed as the best selection for applications, since it provides superior system characteristics with minimum computing time, compared to other methods. In addition, the Gauss quadrature formula with local refinement strategy has been developed for an accurate prediction of the induced velocity computed with the line integration of the Biot–Savart law. Rotary-wing problems including a vortex ring problem are analyzed to show the efficiency, accuracy, and flexibility in the applications of the proposed method.
Evaluation of model fit in nonlinear multilevel structural equation modeling
Directory of Open Access Journals (Sweden)
Karin eSchermelleh-Engel
2014-03-01
Full Text Available Evaluating model fit in nonlinear multilevel structural equation models (MSEM presents a challenge as no adequate test statistic is available. Nevertheless, using a product indicator approach a likelihood ratio test for linear models is provided which may also be useful for nonlinear MSEM. The main problem with nonlinear models is that product variables are nonnormally distributed. Although robust test statistics have been developed for linear SEM to ensure valid results under the condition of nonnormality, they were not yet investigated for nonlinear MSEM. In a Monte Carlo study, the performance of the robust likelihood ratio test was investigated for models with single-level latent interaction effects using the unconstrained product indicator approach. As overall model fit evaluation has a potential limitation in detecting the lack of fit at a single level even for linear models, level-specific model fit evaluation was also investigated using partially saturated models. Four population models were considered: a model with interaction effects at both levels, an interaction effect at the within-group level, an interaction effect at the between-group level, and a model with no interaction effects at both levels. For these models the number of groups, predictor correlation, and model misspecification was varied. The results indicate that the robust test statistic performed sufficiently well. Advantages of level-specific model fit evaluation for the detection of model misfit are demonstrated.
Evaluation of model fit in nonlinear multilevel structural equation modeling.
Schermelleh-Engel, Karin; Kerwer, Martin; Klein, Andreas G
2014-01-01
Evaluating model fit in nonlinear multilevel structural equation models (MSEM) presents a challenge as no adequate test statistic is available. Nevertheless, using a product indicator approach a likelihood ratio test for linear models is provided which may also be useful for nonlinear MSEM. The main problem with nonlinear models is that product variables are non-normally distributed. Although robust test statistics have been developed for linear SEM to ensure valid results under the condition of non-normality, they have not yet been investigated for nonlinear MSEM. In a Monte Carlo study, the performance of the robust likelihood ratio test was investigated for models with single-level latent interaction effects using the unconstrained product indicator approach. As overall model fit evaluation has a potential limitation in detecting the lack of fit at a single level even for linear models, level-specific model fit evaluation was also investigated using partially saturated models. Four population models were considered: a model with interaction effects at both levels, an interaction effect at the within-group level, an interaction effect at the between-group level, and a model with no interaction effects at both levels. For these models the number of groups, predictor correlation, and model misspecification was varied. The results indicate that the robust test statistic performed sufficiently well. Advantages of level-specific model fit evaluation for the detection of model misfit are demonstrated.
Automatic Curve Fitting Based on Radial Basis Functions and a Hierarchical Genetic Algorithm
Directory of Open Access Journals (Sweden)
G. Trejo-Caballero
2015-01-01
Full Text Available Curve fitting is a very challenging problem that arises in a wide variety of scientific and engineering applications. Given a set of data points, possibly noisy, the goal is to build a compact representation of the curve that corresponds to the best estimate of the unknown underlying relationship between two variables. Despite the large number of methods available to tackle this problem, it remains challenging and elusive. In this paper, a new method to tackle such problem using strictly a linear combination of radial basis functions (RBFs is proposed. To be more specific, we divide the parameter search space into linear and nonlinear parameter subspaces. We use a hierarchical genetic algorithm (HGA to minimize a model selection criterion, which allows us to automatically and simultaneously determine the nonlinear parameters and then, by the least-squares method through Singular Value Decomposition method, to compute the linear parameters. The method is fully automatic and does not require subjective parameters, for example, smooth factor or centre locations, to perform the solution. In order to validate the efficacy of our approach, we perform an experimental study with several tests on benchmarks smooth functions. A comparative analysis with two successful methods based on RBF networks has been included.
Nonlinear vibrations of functionally graded doubly curved shallow shells
Alijani, F.; Amabili, M.; Karagiozis, K.; Bakhtiari-Nejad, F.
2011-03-01
Nonlinear forced vibrations of FGM doubly curved shallow shells with a rectangular base are investigated. Donnell's nonlinear shallow-shell theory is used and the shell is assumed to be simply supported with movable edges. The equations of motion are reduced using the Galerkin method to a system of infinite nonlinear ordinary differential equations with quadratic and cubic nonlinearities. Using the multiple scales method, primary and subharmonic resonance responses of FGM shells are fully discussed and the effect of volume fraction exponent on the internal resonance conditions, softening/hardening behavior and bifurcations of the shallow shell when the excitation frequency is (i) near the fundamental frequency and (ii) near two times the fundamental frequency is shown. Moreover, using a code based on arclength continuation method, a bifurcation analysis is carried out for a special case with two-to-one internal resonance between the first and second doubly symmetric modes with respect to the panel's center ( ω13≈2 ω11). Bifurcation diagrams and Poincaré maps are obtained through direct time integration of the equations of motion and chaotic regions are shown by calculating Lyapunov exponents and Lyapunov dimension.
Nonlinear analysis of doubly curved shells: An analytical approach
Indian Academy of Sciences (India)
Y Nath; K Sandeep
2000-08-01
Dynamic analogues of vin Karman-Donnell type shell equations for doubly curved, thin isotropic shells in rectangular planform are formulated and expressed in displacement components. These nonlinear partial differential equations of motion are linearized by using a quadratic extrapolation technique. The spatial and temporal discretization of differential equatoins have been carried out by finite-degree Chebyshev polynomials and implicit Houbolt time-marching techniques respectively. Multiple regression besed on the least square error norm is employed to eliminate the incompatability generated due to spatial discretization (equations > unknowns). Spatial convergence study revealed that nine term expansion of each displacement in and respectively, is sufficient to yield fairly accurate results. Clamped and simply supported immovable doubly curved shallow shells are analysed. Results have been compared with those obtained by other numerical methods. Considering uniformly distributed normal loading, the results of static and dynamic analyses are presented.
Fitting and forecasting non-linear coupled dark energy
Casas, Santiago; Baldi, Marco; Pettorino, Valeria; Vollmer, Adrian
2015-01-01
We consider cosmological models in which dark matter feels a fifth force mediated by the dark energy scalar field, also known as coupled dark energy. Our interest resides in estimating forecasts for future surveys like Euclid when we take into account non-linear effects, relying on new fitting functions that reproduce the non-linear matter power spectrum obtained from N-body simulations. We obtain fitting functions for models in which the dark matter-dark energy coupling is constant. Their validity is demonstrated for all available simulations in the redshift range $z=0-1.6$ and wave modes below $k=10 \\text{h/Mpc}$. These fitting formulas can be used to test the predictions of the model in the non-linear regime without the need for additional computing-intensive N-body simulations. We then use these fitting functions to perform forecasts on the constraining power that future galaxy-redshift surveys like Euclid will have on the coupling parameter, using the Fisher matrix method for galaxy clustering (GC) and w...
Nonlinear Time Series Analysis of White Dwarf Light Curves
Jevtic, N.; Zelechoski, S.; Feldman, H.; Peterson, C.; Schweitzer, J.
2001-12-01
We use nonlinear time series analysis methods to examine the light intensity curves of white dwarf PG1351+489 obtained by the Whole Earth Telescope (WET). Though these methods were originally introduced to study chaotic systems, when a clear signature of determinism is found for the process generating an observable and it couples the active degrees of freedom of the system, then the notion of phase space provides a framework for exploring the system dynamics of nonlinear systems in general. With a pronounced single frequency, its harmonics and other frequencies of lower amplitude on a broadband background, the PG1351 light curve lends itself to the use of time delay coordinates. Our phase space reconstruction yields a triangular, toroidal three-dimensional shape. This differs from earlier results of a circular toroidal representation. We find a morphological similarity to a magnetic dynamo model developed for fast rotators that yields a union of both results: the circular phase space structure for the ascending portion of the cycle, and the triangular structure for the declining portion. The rise and fall of the dynamo cycle yield both different phase space representations and different correlation dimensions. Since PG1351 is known to have no significant fields, these results may stimulate the observation of light curves of known magnetic white dwarfs for comparison. Using other data obtained by the WET, we compare the phase space reconstruction of DB white dwarf PG1351 with that of GD 358 which has a more complex power spectrum. We also compare these results with those for PG1159. There is some general similarity between the results of the phase space reconstruction for the DB white dwarfs. As expected, the difference between the results for the DB white dwarfs and PG1159 is great.
A unified approach to kinematic synthesis of mechanism by adaptive curve fitting
Institute of Scientific and Technical Information of China (English)
WANG; Delun; WANG; Shufen
2004-01-01
A unified approach to kinematic synthesis of mechanism is presented in this paper. Firstly a new approach to adaptive curve fitting is presented, which leads the normal fitting error to be minimum for a series of given discrete points, including a plane curve fitting, a spherical curve fitting and a ruled surface fitting in terms of invariants of ruled surface. Approximate characteristic points and lines are defined, such as an approximate circle point, an approximate slide point, an approximate spherical cone point and an approximate constant axis with an approximate spherical image cone point and an approximate striction curve. Then,the ruled surface fitting will be converted into a space curve fitting and a spherical curve fitting by differential geometry. Based on these definitions and the adaptive curve fitting approaches, the unified mathematical model is set up for the kinematic synthesis of mechanism from planar, spherical to spatial motion. Finally, a planar mechanism or a spatial mechanism can be synthesized by means of searching for two approximate characteristic points, or a characteristic point and a characteristic line, even two characteristic lines. This puper lays a theoretic base for the existence of the best solution and the convergence of the optimum algorithm.
A New Finite Interval Lifetime Distribution Model for Fitting Bathtub-Shaped Failure Rate Curve
Directory of Open Access Journals (Sweden)
Xiaohong Wang
2015-01-01
Full Text Available This paper raised a new four-parameter fitting model to describe bathtub curve, which is widely used in research on components’ life analysis, then gave explanation of model parameters, and provided parameter estimation method as well as application examples utilizing some well-known lifetime data. By comparative analysis between the new model and some existing bathtub curve fitting model, we can find that the new fitting model is very convenient and its parameters are clear; moreover, this model is of universal applicability which is not only suitable for bathtub-shaped failure rate curves but also applicable for the constant, increasing, and decreasing failure rate curves.
Catmull-Rom Curve Fitting and Interpolation Equations
Jerome, Lawrence
2010-01-01
Computer graphics and animation experts have been using the Catmull-Rom smooth curve interpolation equations since 1974, but the vector and matrix equations can be derived and simplified using basic algebra, resulting in a simple set of linear equations with constant coefficients. A variety of uses of Catmull-Rom interpolation are demonstrated,…
Catmull-Rom Curve Fitting and Interpolation Equations
Jerome, Lawrence
2010-01-01
Computer graphics and animation experts have been using the Catmull-Rom smooth curve interpolation equations since 1974, but the vector and matrix equations can be derived and simplified using basic algebra, resulting in a simple set of linear equations with constant coefficients. A variety of uses of Catmull-Rom interpolation are demonstrated,…
Improved treatment of the strongly varying slope in fitting solar cell I-V curves
Energy Technology Data Exchange (ETDEWEB)
Burgers, A.R.; Eikelboom, J.A.; Schoenecker, A.; Sinke, W.C.
1996-05-01
Straightforward least squares fitting of l-V curves leads to non optimal fits: residuals around and above the open-circuit voltage dominate the fit, leading to a bad fit at the maximum power point and lower voltage values. To deal with this problem, the authors have resorted to using weighting functions or to minimizing the area between data and fit instead of the least squares procedure. Both approaches lack a sound statistical basis. Voltage noise has a big influence on fitting due to the steep slope of an l-V curve for higher voltage values. For this reason the authors have used Orthogonal Distance Regression (ODR), which is a mathematical method for fitting measurements with errors in both voltage- and current measurements. It allows for computing both the l-V curve parameters and their uncertainties. 4 figs., 1 tab., 12 refs.
Hossein-Zadeh, Navid Ghavi
2016-08-01
The aim of this study was to compare seven non-linear mathematical models (Brody, Wood, Dhanoa, Sikka, Nelder, Rook and Dijkstra) to examine their efficiency in describing the lactation curves for milk fat to protein ratio (FPR) in Iranian buffaloes. Data were 43 818 test-day records for FPR from the first three lactations of Iranian buffaloes which were collected on 523 dairy herds in the period from 1996 to 2012 by the Animal Breeding Center of Iran. Each model was fitted to monthly FPR records of buffaloes using the non-linear mixed model procedure (PROC NLMIXED) in SAS and the parameters were estimated. The models were tested for goodness of fit using Akaike's information criterion (AIC), Bayesian information criterion (BIC) and log maximum likelihood (-2 Log L). The Nelder and Sikka mixed models provided the best fit of lactation curve for FPR in the first and second lactations of Iranian buffaloes, respectively. However, Wood, Dhanoa and Sikka mixed models provided the best fit of lactation curve for FPR in the third parity buffaloes. Evaluation of first, second and third lactation features showed that all models, except for Dijkstra model in the third lactation, under-predicted test time at which daily FPR was minimum. On the other hand, minimum FPR was over-predicted by all equations. Evaluation of the different models used in this study indicated that non-linear mixed models were sufficient for fitting test-day FPR records of Iranian buffaloes.
Basic Searching, Interpolating, and Curve-Fitting Algorithms in C++
2015-01-01
for best-fit equations. Functions for working with periodic equations are included. 15. SUBJECT TERMS interpolate , linear, cubic, hermite, polynomial ...Periodic Interpolations 17 11. Example: Determining Interpolation Performance 18 12. Example: Interpolating in Two Dimensions 19 13. Polynomial ...cubic Hermite spline is a third-degree- polynomial interpolating function that is uniquely determined by 2 endpoint positions ( 0p and 1p ) and
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.
Directory of Open Access Journals (Sweden)
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.
A polarimetric study of asteroids: Fitting phase - polarization curves
Cellino, A; Gil-Hutton, R; Tanga, P; Canada-Assandri, M; Tedesco, E F
2015-01-01
By considering all asteroid linear polarization data available in the literature, it is possible to obtain updated phase - polarization curves for several tens of objects. In a separate paper (Cellino et al., 2015a, MNRAS, 451, 3473) we have produced new calibrations of different relations between the geometric albedo and several polarimetric parameters, based on an analysis of a limited sample of asteroids for which the albedo is known with sufficient accuracy. In this paper, we present the main polarization parameters and corresponding albedos for a larger dataset of asteroids which we did not use for calibration purposes. We find a good agreement between the albedo values computed using different polarization parameters. Conversely, in the case of the so-called Barbarian asteroids the situation is rather unclear. Moreover, we present an updated analysis of the distributions of different polarimetric parameters, including the so-called inversion angle and the solar phase angle corresponding to the extreme v...
Limitations in biexponential fitting of NMR inversion-recovery curves
Shazeeb, Mohammed Salman; Sotak, Christopher H.
2017-03-01
NMR relaxation agents have long been employed as contrast agents in MRI. In many cases, the contrast agent is confined to either (i) the vascular and/or extracellular compartment (EC), as is the case with gadolinium(III)-based agents, or (ii) the intracellular compartment (IC), as is the case with manganese(II) ions. The compartmentalization of contrast agents often results in tissue-water 1H relaxation profiles that are well modeled as biexponential. It has long been recognized that water exchange between compartments modifies the biexponential relaxation parameters (amplitudes and rate constants) from those that would be found in the absence of exchange. Nevertheless, interpretation in terms of an ;apparent; two-compartment biophysical model, apparent EC vs. apparent IC, can provide insight into tissue structure and function, and changes therein, in the face of physiologic challenge. The accuracy of modeling biexponential data is highly dependent upon the amplitudes, rate constants, and signal-to-noise characterizing the data. Herein, simulated (in silico) inversion-recovery relaxation data are modeled by standard, nonlinear-least-squares analysis and the error in parameter values assessed for a range of amplitudes and rate constants characteristic of in vivo systems following administration of contrast agent. The findings provide guidance for laboratories seeking to exploit contrast-agent-driven, biexponential relaxation to differentiate MRI-based compartmental properties, including the apparent diffusion coefficient.
A Grid Algorithm for High Throughput Fitting of Dose-Response Curve Data
Wang, Yuhong; Jadhav, Ajit; Southal, Noel; Huang, Ruili; Nguyen, Dac-Trung
2010-01-01
We describe a novel algorithm, Grid algorithm, and the corresponding computer program for high throughput fitting of dose-response curves that are described by the four-parameter symmetric logistic dose-response model. The Grid algorithm searches through all points in a grid of four dimensions (parameters) and finds the optimum one that corresponds to the best fit. Using simulated dose-response curves, we examined the Grid program’s performance in reproducing the actual values that were used ...
Institute of Scientific and Technical Information of China (English)
毛永江; 张美荣; 许兆君; 刘姗; 张亚琴; 陈丹; 王杏龙; 杨章平
2012-01-01
旨在了解南方中国荷斯坦牛测定日产奶量、乳脂率、乳蛋白率和体细胞评分(Somatic cell score,SCS)变化趋势,并进行准确预测.利用Wood模型对南方5个大中型奶牛场(2008-2010年1～3胎)中国荷斯坦牛的33 194条测定日产奶量、乳脂率、乳蛋白率和SCS数据进行曲线拟合.结果表明,测定日产奶量为标准泌乳曲线,乳脂率、乳蛋白率和SCS变化与标准泌乳曲线正好相反.Wood模型对乳蛋白率和产奶量变化曲线拟合度最高,各胎次拟合度均为0.99,误差均方也较低；其次为乳脂率,各胎次拟合度均为0.98,而对SCS的拟合度最低,均在0.7以下,同时误差均方也最大.各胎次产奶高峰日出现的时间与乳蛋白率和SCS最低值出现的时间相近,而最低乳脂率出现的时间较晚.一胎牛高峰产奶量相对较低(30.4 kg·d-1),但泌乳后期泌乳持续力及维持低SCS能力较强；二胎和三胎牛高峰产奶量较大,分别为35.9和36.2 kg·d-1,二胎奶牛在泌乳后期同时维持高乳脂率和乳蛋白率的能力较强.Wood模型适合于南方中国荷斯坦牛测定日产奶量、乳脂率、乳蛋白率变化曲线的拟合分析,而不适合于SCS的拟合分析.%This study aimed to reveal the variations of daily milk yield, milk fat percentage, milk protein percentage and somatic cell score (SCS) , and to establish the prediction models for these parameters in the lactation period for Chinese Holstein in southern China. A 33194-test-day dairy herd complete data from 5 Chinese Holstein dairy farms were collected in the southern China from first lactation to third lactation between 2008 to 2010 and fitted to nonlinear curve of test-day milk yield, milk fat percentage, milk protein percentage and SCS with the Wood's incomplete gamma function model. The curve of test-day milk yield for Chinese Holstein was the standard lactation curve, and the curves of milk fat percentage, milk protein percentage and SCS were
"Asymptotic Parabola" Fits for Smoothing Generally Asymmetric Light Curves
Andrych, Kateryna D; Chinarova, Lidia L; Marsakova, Vladyslava I
2015-01-01
A computer program is introduced, which allows to determine statistically optimal approxi-mation using the "Asymptotic Parabola" fit, or, in other words, the spline consisting of polynomials of order 1,2,1, or two lines ("asymptotes") connected with a parabola. The function itself and its derivative is continuous. There are 5 parameters: two points, where a line switches to a parabola and vice versa, the slopes of the line and the curvature of the parabola. Extreme cases are either the parabola without lines (i.e.the parabola of width of the whole interval), or lines without a parabola (zero width of the parabola), or "line+parabola" without a second line. Such an approximation is especially effective for pulsating variables, for which the slopes of the ascending and descending branches are generally different, so the maxima and minima have asymmetric shapes. The method was initially introduced by Marsakova and Andronov (1996OAP.....9..127M) and realized as a computer program written in QBasic under DOS. It w...
A Methodology for Curve and Surface Fitting with Adaptive Fairing for Digitized Points
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A new approach for NURBS (Non-uniform rational B-spline) curve and surface fitting for measured points was presented which employs a fairing method applied to digitized point data with discrete curvature. If measured points are used as control points to construct an NURBS curve, then the curvature of each data point corresponding to control point of the constructed curve can be computed. According to the convex hull andlocal properties of NURBS, based on the curvatures obtained, the measured points can be faired. If faired measured points are used as target points to modify, the constructed curve passing through these faired points can produce a smooth NURBS curve. This paper also presented the justification for utilizing the curvatures of constructed NURBS curve instead of the conventional interpolated curve to fair the measured points. Based on the presented algorithms, some qualities of the constructed curves can be improved.
Fit of different linear models to the lactation curve of Italian water buffalo
Directory of Open Access Journals (Sweden)
N.P.P. Macciotta
2010-01-01
Full Text Available Mathematical modelling of lactation curve by suitable functions of time, widely used in the dairy cattle industry, can represent also for buffaloes a fundamental tool for management and breeding decision, where average curves are considered, and for genetic evaluation by random regression models, where individual patterns are fitted.
Non-linear Least-squares Fitting in IDL with MPFIT
Markwardt, C. B.
2009-09-01
MPFIT is a port to IDL of the non-linear least squares fitting program MINPACK-1. MPFIT inherits the robustness of the original FORTRAN version of MINPACK-1, but is optimized for performance and convenience in IDL. In addition to the main fitting engine, MPFIT, several specialized functions are provided to fit 1-D curves and 2-D images, 1-D and 2-D peaks, and interactive fitting from the IDL command line. Several constraints can be applied to model parameters, including fixed constraints, simple bounding constraints, and ``tying'' the value to another parameter. Several data-weighting methods are allowed, and the parameter covariance matrix is computed. Extensive diagnostic capabilities are available during the fit, via a call-back subroutine, and after the fit is complete. Several different forms of documentation are provided, including a tutorial, reference pages, and frequently asked questions. The package has been translated to C and Python as well. The full IDL and C packages can be found at http://purl.com/net/mpfit.
Nonlinear least-squares data fitting in Excel spreadsheets.
Kemmer, Gerdi; Keller, Sandro
2010-02-01
We describe an intuitive and rapid procedure for analyzing experimental data by nonlinear least-squares fitting (NLSF) in the most widely used spreadsheet program. Experimental data in x/y form and data calculated from a regression equation are inputted and plotted in a Microsoft Excel worksheet, and the sum of squared residuals is computed and minimized using the Solver add-in to obtain the set of parameter values that best describes the experimental data. The confidence of best-fit values is then visualized and assessed in a generally applicable and easily comprehensible way. Every user familiar with the most basic functions of Excel will be able to implement this protocol, without previous experience in data fitting or programming and without additional costs for specialist software. The application of this tool is exemplified using the well-known Michaelis-Menten equation characterizing simple enzyme kinetics. Only slight modifications are required to adapt the protocol to virtually any other kind of dataset or regression equation. The entire protocol takes approximately 1 h.
Potential errors when fitting experience curves by means of spreadsheet software
Energy Technology Data Exchange (ETDEWEB)
Van Sark, W.G.J.H.M.; Alsema, E.A. [Department of Science, Technology and Society, Copernicus Institute, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht (Netherlands)
2010-11-15
Progress ratios (PRs) are widely used in forecasting development of many technologies; they are derived from historical data represented in experience curves. Fitting the double logarithmic graphs is easily done with spreadsheet software like Microsoft Excel, by adding a trend line to the graph. However, it is unknown to many that these data are transformed to linear data before a fit is performed. This leads to erroneous results or a transformation bias in the PR, as we demonstrate using the experience curve for photovoltaic technology: logarithmic transformation leads to overestimates of progress ratios and underestimates of goodness of fit. Therefore, other graphing and analysis software is recommended. (author)
Potential errors when fitting experience curves by means of spreadsheet software
Energy Technology Data Exchange (ETDEWEB)
Sark, W.G.J.H.M. van, E-mail: w.g.j.h.m.vansark@uu.n [Department of Science, Technology and Society, Copernicus Institute, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht (Netherlands); Alsema, E.A. [Department of Science, Technology and Society, Copernicus Institute, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht (Netherlands)
2010-11-15
Progress ratios (PRs) are widely used in forecasting development of many technologies; they are derived from historical data represented in experience curves. Fitting the double logarithmic graphs is easily done with spreadsheet software like Microsoft Excel, by adding a trend line to the graph. However, it is unknown to many that these data are transformed to linear data before a fit is performed. This leads to erroneous results or a transformation bias in the PR, as we demonstrate using the experience curve for photovoltaic technology: logarithmic transformation leads to overestimates of progress ratios and underestimates of goodness of fit. Therefore, other graphing and analysis software is recommended.
IDENTIFICATION OF NONLINEAR DYNAMIC SYSTEMS:TIME-FREQUENCY FILTERING AND SKELETON CURVES
Institute of Scientific and Technical Information of China (English)
王丽丽; 张景绘
2001-01-01
The nonlinear behavior varying with the instantaneous response was analyzed through the joint time-frequency analysis method for a class of S. D. O . F nonlinear system.A masking operator on definite regions is defined and two theorems are presented. Based on these, the nonlinear system is modeled with a special time-varying linear one, called the generalized skeleton linear system ( GSLS ). The frequency skeleton curve and the damping skeleton curve are defined to describe the main feature of the non-linearity as well. More over, an identification method is proposed through the skeleton curves and the time frequency filtering technique.
A grid algorithm for high throughput fitting of dose-response curve data.
Wang, Yuhong; Jadhav, Ajit; Southal, Noel; Huang, Ruili; Nguyen, Dac-Trung
2010-10-21
We describe a novel algorithm, Grid algorithm, and the corresponding computer program for high throughput fitting of dose-response curves that are described by the four-parameter symmetric logistic dose-response model. The Grid algorithm searches through all points in a grid of four dimensions (parameters) and finds the optimum one that corresponds to the best fit. Using simulated dose-response curves, we examined the Grid program's performance in reproducing the actual values that were used to generate the simulated data and compared it with the DRC package for the language and environment R and the XLfit add-in for Microsoft Excel. The Grid program was robust and consistently recovered the actual values for both complete and partial curves with or without noise. Both DRC and XLfit performed well on data without noise, but they were sensitive to and their performance degraded rapidly with increasing noise. The Grid program is automated and scalable to millions of dose-response curves, and it is able to process 100,000 dose-response curves from high throughput screening experiment per CPU hour. The Grid program has the potential of greatly increasing the productivity of large-scale dose-response data analysis and early drug discovery processes, and it is also applicable to many other curve fitting problems in chemical, biological, and medical sciences.
Note: curve fit models for atomic force microscopy cantilever calibration in water.
Kennedy, Scott J; Cole, Daniel G; Clark, Robert L
2011-11-01
Atomic force microscopy stiffness calibrations performed on commercial instruments using the thermal noise method on the same cantilever in both air and water can vary by as much as 20% when a simple harmonic oscillator model and white noise are used in curve fitting. In this note, several fitting strategies are described that reduce this difference to about 11%. © 2011 American Institute of Physics
Nonlinear Latent Curve Models for Multivariate Longitudinal Data
Blozis, Shelley A.; Conger, Katherine J.; Harring, Jeffrey R.
2007-01-01
Latent curve models have become a useful approach to analyzing longitudinal data, due in part to their allowance of and emphasis on individual differences in features that describe change. Common applications of latent curve models in developmental studies rely on polynomial functions, such as linear or quadratic functions. Although useful for…
Institute of Scientific and Technical Information of China (English)
WangLin; NiQiao; HuangYuying
2003-01-01
This paper proposes a new method for investigating the Hopf bifurcation of a curved pipe conveying fluid with nonlinear spring support. The nonlinear equation of motion is derived by forces equilibrium on microelement of the system under consideration. The spatial coordinate of the system is discretized by the differential quadrature method and then the dynamic equation is solved by the Newton-Raphson method. The numerical solutions show that the inner fluid velocity of the Hopf bifurcation point of the curved pipe varies with different values of the parameter,nonlinear spring stiffness. Based on this, the cycle and divergent motions are both found to exist at specific fluid flow velocities with a given value of the nonlinear spring stiffness. The results are useful for further study of the nonlinear dynamic mechanism of the curved fluid conveying pipe.
Potential errors when fitting experience curves by means of spreadsheet software
van Sark, W.G.J.H.M.; Alsema, E.A.
2010-01-01
Progress ratios (PRs) are widely used in forecasting development of many technologies; they are derived from historical data represented in experience curves. Fitting the double logarithmic graphs is easily done with spreadsheet software like Microsoft Excel, by adding a trend line to the graph. How
Wang, Chee Keng John; Pyun, Do Young; Liu, Woon Chia; Lim, Boon San Coral; Li, Fuzhong
2013-01-01
Using a multilevel latent growth curve modeling (LGCM) approach, this study examined longitudinal change in levels of physical fitness performance over time (i.e. four years) in young adolescents aged from 12-13 years. The sample consisted of 6622 students from 138 secondary schools in Singapore. Initial analyses found between-school variation on…
Wang, Chee Keng John; Pyun, Do Young; Liu, Woon Chia; Lim, Boon San Coral; Li, Fuzhong
2013-01-01
Using a multilevel latent growth curve modeling (LGCM) approach, this study examined longitudinal change in levels of physical fitness performance over time (i.e. four years) in young adolescents aged from 12-13 years. The sample consisted of 6622 students from 138 secondary schools in Singapore. Initial analyses found between-school variation on…
Kilian, Gladiné; Pieter, Muyshondt; Joris, Dirckx
2016-06-01
Laser Doppler Vibrometry is an intrinsic highly linear measurement technique which makes it a great tool to measure extremely small nonlinearities in the vibration response of a system. Although the measurement technique is highly linear, other components in the experimental setup may introduce nonlinearities. An important source of artificially introduced nonlinearities is the speaker, which generates the stimulus. In this work, two correction methods to remove the effects of stimulus nonlinearity are investigated. Both correction methods were found to give similar results but have different pros and cons. The aim of this work is to investigate the importance of the conical shape of the eardrum as a source of nonlinearity in hearing. We present measurements on flat and indented membranes. The data shows that the curved membrane exhibit slightly higher levels of nonlinearity compared to the flat membrane.
Cigeroglu, Ender; Samandari, Hamed
2014-11-01
Nonlinear free vibration analysis of curved double-walled carbon nanotubes (DWNTs) embedded in an elastic medium is studied in this study. Nonlinearities considered are due to large deflection of carbon nanotubes (geometric nonlinearity) and nonlinear interlayer van der Waals forces between inner and outer tubes. The differential quadrature method (DQM) is utilized to discretize the partial differential equations of motion in spatial domain, which resulted in a nonlinear set of algebraic equations of motion. The effect of nonlinearities, different end conditions, initial curvature, and stiffness of the surrounding elastic medium, and vibrational modes on the nonlinear free vibration of DWCNTs is studied. Results show that it is possible to detect different vibration modes occurring at a single vibration frequency when CNTs vibrate in the out-of-phase vibration mode. Moreover, it is observed that boundary conditions have significant effect on the nonlinear natural frequencies of the DWCNT including multiple solutions.
Seismic Fragility Curves of Industrial Buildings by Using Nonlinear Analysis
Directory of Open Access Journals (Sweden)
Mohamed Nazri Fadzli
2017-01-01
Full Text Available This study presents the steel fragility curves and performance curves of industrial buildings of different geometries. The fragility curves were obtained for different building geometries, and the performance curves were developed based on lateral load, which is affected by the geometry of the building. Three records of far-field ground motion were used for incremental dynamic analysis (IDA, and the design lateral loads for pushover analysis (POA. All designs were based on British Standard (BS 5950; however, Eurocode 8 was preferred for seismic consideration in the analysis because BS 5950 does not specify any seismic provision. The five levels of performance stated by FEMA-273, namely, operational phase, immediate occupancy, damage control, life safety, and collapse prevention (CP were used as main guidelines for evaluating structural performance. For POA, Model 2 had highest base shear, followed by Model 1 and Model 3, even though Model 2 has a smaller structure compared with Model 3. Meanwhile, the fragility curves showed that the probability of reaching or exceeding the CP level of Model 2 is the highest, followed by that of Models 1 and 3.
Edge detection of remote sensing image based on nonlinear intensity of curved surface
Institute of Scientific and Technical Information of China (English)
张连蓬; 刘国林; 江涛
2003-01-01
A new edge detector based on the nonlinear intensity of curved surface was proposed. The edge detector describes the largest curvature and the smallest curvature of curved surface, therefore it can reflect the real largest direction of image edge jump. By the new edge detector, it is convenient to calculate the curvature in any direction of the curved surface and the curvature can be used in the identification of edge direction and the feature extraction of objects on remote sensing image.
Directory of Open Access Journals (Sweden)
Henley William
2011-10-01
Full Text Available Abstract Background Mean costs and quality-adjusted-life-years are central to the cost-effectiveness of health technologies. They are often calculated from time to event curves such as for overall survival and progression-free survival. Ideally, estimates should be obtained from fitting an appropriate parametric model to individual patient data. However, such data are usually not available to independent researchers. Instead, it is common to fit curves to summary Kaplan-Meier graphs, either by regression or by least squares. Here, a more accurate method of fitting survival curves to summary survival data is described. Methods First, the underlying individual patient data are estimated from the numbers of patients at risk (or other published information and from the Kaplan-Meier graph. The survival curve can then be fit by maximum likelihood estimation or other suitable approach applied to the estimated individual patient data. The accuracy of the proposed method was compared against that of the regression and least squares methods and the use of the actual individual patient data by simulating the survival of patients in many thousands of trials. The cost-effectiveness of sunitinib versus interferon-alpha for metastatic renal cell carcinoma, as recently calculated for NICE in the UK, is reassessed under several methods, including the proposed method. Results Simulation shows that the proposed method gives more accurate curve fits than the traditional methods under realistic scenarios. Furthermore, the proposed method achieves similar bias and mean square error when estimating the mean survival time to that achieved by analysis of the complete underlying individual patient data. The proposed method also naturally yields estimates of the uncertainty in curve fits, which are not available using the traditional methods. The cost-effectiveness of sunitinib versus interferon-alpha is substantially altered when the proposed method is used. Conclusions
NON-STATIONARY SIGNAL DENOISING USING TIME-FREQUENCY CURVE SURFACE FITTING
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Based on the theory of adaptive time-frequency decomposition and Time-Frequency Distribution Series (TFDS), this paper presents a novel denoising method for non-stationary signal. According to the input signal features, an appropriate kind of elementary functions with great concentration in the Time-Frequency (TF) plane is selected. Then the input signal is decomposed into a linear combination of these functions. The elementary function parameters are determined by using elementary function TF curve surface to fit the input signal's TFDS. The process of curved surface fitting corresponds to the signal structure matching process. The input signal's dominating component whose structure has the resemblance with elementary function is fitted out firstly. Repeating the fitting process, the residue can be regarded as noises, which are greatly different from the function. Selecting the functions fitted out initially for reconstruction, the denoised signal is obtained. The performance of the proposed method is assessed by means of several tests on an emulated signal and a gearbox vibrating signal.
Liao, Fei; Zhu, Xiao-Yun; Wang, Yong-Mei; Zuo, Yu-Ping
2005-01-31
The estimation of enzyme kinetic parameters by nonlinear fitting reaction curve to the integrated Michaelis-Menten rate equation ln(S(0)/S)+(S(0)-S)/K(m)=(V(m)/K(m))xt was investigated and compared to that by fitting to (S(0)-S)/t=V(m)-K(m)x[ln(S(0)/S)/t] (Atkins GL, Nimmo IA. The reliability of Michaelis-Menten constants and maximum velocities estimated by using the integrated Michaelis-Menten equation. Biochem J 1973;135:779-84) with uricase as the model. Uricase reaction curve was simulated with random absorbance error of 0.001 at 0.075 mmol/l uric acid. Experimental reaction curve was monitored by absorbance at 293 nm. For both CV and deviation kinetic parameters and applicable for the characterization of enzyme inhibitors.
A novel graph computation technique for multi-dimensional curve fitting
Motlagh, O.; Tang, S. H.; Maslan, M. N.; Azni Jafar, Fairul; Aziz, Maslita A.
2013-06-01
Curve-fitting problems are widely solved using numerical and soft techniques. In particular, artificial neural networks (ANN) are used to approximate arbitrary input-output relationships in the form of tuned edge weights. Moreover, using semantic networks such as fuzzy cognitive map (FCM), single graph nodes could be directly associated with their actual grey scales rather than binary values as in ANN. This article examines a novel methodology for automatic construction of FCMs for function approximation. The main contribution is the introduction of nested-FCM structure for multi-variable curve fitting. There are step-by-step example cases along with the obtained results to serve as a guide to the new methods being introduced. It is shown that nested FCM derives relationship models of multiple variables using any conventional weight training technique with minimal computation effort. Issues about computational cost and accuracy are also discussed along with future direction of the research.
The Predicting Model of E-commerce Site Based on the Ideas of Curve Fitting
Tao, Zhang; Li, Zhang; Dingjun, Chen
On the basis of the idea of the second multiplication curve fitting, the number and scale of Chinese E-commerce site is analyzed. A preventing increase model is introduced in this paper, and the model parameters are solved by the software of Matlab. The validity of the preventing increase model is confirmed though the numerical experiment. The experimental results show that the precision of preventing increase model is ideal.
Constructing iterative non-uniform B-spline curve and surface to fit data points
Institute of Scientific and Technical Information of China (English)
LIN Hongwei; WANG Guojin; DONG Chenshi
2004-01-01
In this paper, based on the idea of profit and loss modification, we present the iterative non-uniform B-spline curve and surface to settle a key problem in computer aided geometric design and reverse engineering, that is, constructing the curve (surface)fitting (interpolating) a given ordered point set without solving a linear system. We start with a piece of initial non-uniform B-spline curve (surface) which takes the given point set as its control point set. Then by adjusting its control points gradually with iterative formula,we can get a group of non-uniform B-spline curves (surfaces) with gradually higher precision. In this paper, using modern matrix theory, we strictly prove that the limit curve (surface) of the iteration interpolates the given point set. The non-uniform B-spline curves (surfaces) generated with the iteration have many advantages, such as satisfying the NURBS standard, having explicit expression, gaining locality, and convexity preserving,etc.
PV Degradation Curves: Non-Linearities and Failure Modes
Energy Technology Data Exchange (ETDEWEB)
Jordan, Dirk C.; Silverman, Timothy J.; Sekulic, Bill; Kurtz, Sarah R.
2016-09-03
Photovoltaic (PV) reliability and durability have seen increased interest in recent years. Historically, and as a preliminarily reasonable approximation, linear degradation rates have been used to quantify long-term module and system performance. The underlying assumption of linearity can be violated at the beginning of the life, as has been well documented, especially for thin-film technology. Additionally, non-linearities in the wear-out phase can have significant economic impact and appear to be linked to different failure modes. In addition, associating specific degradation and failure modes with specific time series behavior will aid in duplicating these degradation modes in accelerated tests and, eventually, in service life prediction. In this paper, we discuss different degradation modes and how some of these may cause approximately linear degradation within the measurement uncertainty (e.g., modules that were mainly affected by encapsulant discoloration) while other degradation modes lead to distinctly non-linear degradation (e.g., hot spots caused by cracked cells or solder bond failures and corrosion). The various behaviors are summarized with the goal of aiding in predictions of what may be seen in other systems.
Directory of Open Access Journals (Sweden)
Esteban Pérez-López
2014-11-01
Full Text Available Because of the importance of quantitative chemical analysis in research, quality control, sales of services and other areas of interest , and the limiting of some instrumental analysis methods for quantification with linear calibration curve, sometimes because the short linear dynamic ranges of the analyte, and sometimes by limiting the technique itself, is that there is a need to investigate a little more about the convenience of using quadratic curves for analytical quantification, which seeks demonstrate that it is a valid calculation model for chemical analysis instruments. To this was taken as an analysis method based on the technique and atomic absorption spectroscopy in particular a determination of magnesium in a sample of drinking water Tacares sector Northern Grecia, employing a nonlinear calibration curve and a curve specific quadratic behavior, which was compared with the test results obtained for the same analysis with a linear calibration curve. The results show that the methodology is valid for the determination referred to, with all confidence, since the concentrations are very similar, and as used hypothesis testing can be considered equal.
Improved Nonlinear Equation Method for Numerical Prediction of Jominy End-Quench Curves
Institute of Scientific and Technical Information of China (English)
SONG Yue-peng; LIU Guo-quan; LIU Sheng-xin; LIU Jian-tao; FENG Cheng-ming
2007-01-01
Without considering the effects of alloying interaction on the Jominy end-quench curves, the prediction results obtained by YU Bai-hai's nonlinear equation method for multi-alloying steels were different from those experimental ones reported in literature. Some alloying elements have marked influence on Jominy end-quench curves of steels. An improved mathematical model for simulating the Jominy end-quench curves is proposed by introducing a parameter named alloying interactions equivalent (Le). With the improved model, the Jominy end-quench curves of steels so obtained agree very well with the experimental ones.
Ko, William L.; Fleischer, Van Tran; Lung, Shun-Fat
2017-01-01
For shape predictions of structures under large geometrically nonlinear deformations, Curved Displacement Transfer Functions were formulated based on a curved displacement, traced by a material point from the undeformed position to deformed position. The embedded beam (depth-wise cross section of a structure along a surface strain-sensing line) was discretized into multiple small domains, with domain junctures matching the strain-sensing stations. Thus, the surface strain distribution could be described with a piecewise linear or a piecewise nonlinear function. The discretization approach enabled piecewise integrations of the embedded-beam curvature equations to yield the Curved Displacement Transfer Functions, expressed in terms of embedded beam geometrical parameters and surface strains. By entering the surface strain data into the Displacement Transfer Functions, deflections along each embedded beam can be calculated at multiple points for mapping the overall structural deformed shapes. Finite-element linear and nonlinear analyses of a tapered cantilever tubular beam were performed to generate linear and nonlinear surface strains and the associated deflections to be used for validation. The shape prediction accuracies were then determined by comparing the theoretical deflections with the finiteelement- generated deflections. The results show that the newly developed Curved Displacement Transfer Functions are very accurate for shape predictions of structures under large geometrically nonlinear deformations.
Energy Technology Data Exchange (ETDEWEB)
Ying Chen; Shao-Jing Dong; Terrence Draper; Ivan Horvath; Keh-Fei Liu; Nilmani Mathur; Sonali Tamhankar; Cidambi Srinivasan; Frank X. Lee; Jianbo Zhang
2004-05-01
We introduce the ''Sequential Empirical Bayes Method'', an adaptive constrained-curve fitting procedure for extracting reliable priors. These are then used in standard augmented-{chi}{sup 2} fits on separate data. This better stabilizes fits to lattice QCD overlap-fermion data at very low quark mass where a priori values are not otherwise known. Lessons learned (including caveats limiting the scope of the method) from studying artificial data are presented. As an illustration, from local-local two-point correlation functions, we obtain masses and spectral weights for ground and first-excited states of the pion, give preliminary fits for the a{sub 0} where ghost states (a quenched artifact) must be dealt with, and elaborate on the details of fits of the Roper resonance and S{sub 11}(N{sup 1/2-}) previously presented elsewhere. The data are from overlap fermions on a quenched 16{sup 3} x 28 lattice with spatial size La = 3.2 fm and pion mass as low as {approx}180 MeV.
Artificial Neural Networks for Estimating Soil Water Retention Curve Using Fitted and Measured Data
Directory of Open Access Journals (Sweden)
Tirzah Moreira de Melo
2015-01-01
Full Text Available Artificial neural networks for estimating the soil water retention curve have been developed considering measured data and require a large quantity of soil samples because only retention curve data obtained for the same set of matric potentials can be used. In order to preclude this drawback, we present two ANN models which tested the performance of ANNs trained with fitted water contents data. These models were compared to a recent new ANN approach for predicting water retention curve, the pseudocontinuous pedotransfer functions (PTFs, which is also an attempt to deal with limited data. Additionally, a sensitivity analysis was carried out to verify the influence of each input parameter on each output. Results showed that fitted ANNs provided similar statistical indexes in predicting water contents to those obtained by the pseudocontinuous method. Sensitivity analysis revealed that bulk density and porosity are the most important parameters for predicting water contents in wet regime, whereas sand and clay contents are more significant in drier conditions. The sensitivity analysis for the pseudocontinuous method demonstrated that the natural logarithm of the matric potential became the most important parameter, and the influences of all other inputs were reduced to be not relevant, except the bulk density.
Algorithms for l2 and l-infinity transfer function curve fitting
Spanos, John T.
1991-01-01
In this paper algorithms for fitting transfer functions to frequency response data are developed. Given a complex vector representing the measured frequency response of a physical system, a transfer function of specified order is determined that minimizes either of the following criteria: (1) the sum of the magnitude-squared of the frequency response errors, and (2) the magnitude of the maximum error. Both of these criteria are nonlinear in the coefficients of the unknown transfer function, and iterative minimization algorithms are proposed. A numerical example demonstrates the effectiveness of the proposed algorithms.
Institute of Scientific and Technical Information of China (English)
马林; 周惠; 杨丽珍
2012-01-01
为了研究纳米氧化锌光催化降解染料废水的作用，选用甲基橙溶液作为模拟污染物，通过测试甲基橙溶液在光照前后的吸光度来考察纳米氧化锌的光催化效率。使用二元非线性模型对纳米氧化锌光催化甲基橙实验数据进行拟合，对纳米氧化锌光催化甲基橙降解率进行修正。采用溶胶凝胶法制备纳米氧化锌，以20mg／L的甲基橙溶液作为模拟污染物，通过测试紫外光照射前后甲基橙溶液的吸光度来考察纳米氧化锌的光催化性能，对得到的实验数据进行数学拟合。结果表明，甲基橙溶液在紫外光照射下会自行分解，且自身降解符合二元非线性方程。该算法可以实现最优拟合。通过使用此二元非线性公式，可以达到修正纳米氧化锌光催化甲基橙实验数据的目的，氧化锌催化甲基橙降解率计算结果更精确。%In order to study the nano-zinc oxide photocatalytic degradation of dye wastewater role, the selection of methyl orange solution as simulation of pollutants, the test of methyl orange solution absorbance before and after the light examines the photoeatalytic efficiency of nano-zinc oxide. The paper uses the binary non-linear fitting model to fit the data of nano-zinc oxide photocatalytic experiment, amending the degradation rate of nano-zine oxide photoeatalytic methyl orange. The nano-zinc oxide is prepared by sol-gel. Taking 20mg/L methyl orange solution as simulation of pollutants and records the absorbanee of the test before and after UV irradiation of methyl orangesolution to examine the photocatalytic properties of nano-zinc oxide. The results show that the methyl orange solution would be self-decomposition under UV light and the experimental datas obtained fits mathematical and the results indicate that the methyl orange solution degradation is in line with the binary nonlinear equations. The numerical simulation results indicate that the
Pineda, Juan C B; Springel, Volker; de Oliveira, Claudia Mendes
2016-01-01
We study the role of systematic effects in observational studies of the core/cusp problem under the minimum disc approximation using a suite of high-resolution (25-pc softening length) hydrodynamical simulations of dwarf galaxies. We mimic kinematical observations in a realistic manner at different distances and inclinations, and fit the resulting rotation curves with two analytical models commonly used to differentiate cores from cusps in the dark matter distribution. We find that the cored pseudo-isothermal sphere (P-ISO) model is often strongly favoured by the reduced $\\chi^2_\
[Aging Process of Puer Black Tea Studied by FTIR Spectroscopy Combined with Curve-Fitting Analysis].
Li, Dong-yu; Shi, You-ming; Yi, Shi Lai
2015-07-01
For better determination of the chemical components in the Puer black tea, Fourier transform infrared spectroscopy was used for obtaining vibrational spectra of Puer black tea at different aging time. Fourier transform infrared (FTIR) spectra indicated that the chemical components had change in Puer black tea at different aging time. The leaf of Puer black tea was a complex system, its Fourier transform infrared spectrum showed a total overlap of each absorption spectrum of various components. Each band represented an overall overlap of some characteristic absorption peaks of functional groups in the Puer black tea. In order to explore the change of characteristic absorption peaks of functional groups with aging time, the prediction positions and the number of second peaks in the range of 1900-900 cm(-1) were determined by Fourier self-deconvolution at first, and later the curve fitting analysis was performed in this overlap band. At different aging time of Puer black tea, the wave number of second peaks of amide II, tea polyphenol, pectin and polysaccharides at overlap band were assigned by curve fitting analysis. The second peak at 1520 cm(-1) was characteristic absorption band of amide II, the second peaks of tea polyphenol and pectin appeared at 1278 and 1103 cm(-1) respectively. Two second peaks at 1063 and 1037 cm(-1), corresponds mainly to glucomannan and arabinan. The relative area of these second peaks could be indicated the content of protein, tea polyphenol, pectin and polysaccharides in the Puer black tea. The results of curve fitting analysis showed that the relative area of amide II was increasing first and then decreasing, it indicated the change of protein in Puer black tea. At the same time, the content of tea polyphenol and pectin were decreased with the increase of aging time, but the glucomannan and arabinan were increased in reverse. It explained that the bitter taste was become weak and a sweet taste appeared in the tea with the increase of
A novel curve fitting method for AV optimisation of biventricular pacemakers.
Dehbi, Hakim-Moulay; Jones, Siana; Sohaib, S M Afzal; Finegold, Judith A; Siggers, Jennifer H; Stegemann, Berthold; Whinnett, Zachary I; Francis, Darrel P
2015-09-01
In this study, we designed and tested a new algorithm, which we call the 'restricted parabola', to identify the optimum atrioventricular (AV) delay in patients with biventricular pacemakers. This algorithm automatically restricts the hemodynamic data used for curve fitting to the parabolic zone in order to avoid inadvertently selecting an AV optimum that is too long.We used R, a programming language and software environment for statistical computing, to create an algorithm which applies multiple different cut-offs to partition curve fitting of a dataset into a parabolic and a plateau region and then selects the best cut-off using a least squares method. In 82 patients, AV delay was adjusted and beat-to-beat systolic blood pressure (SBP) was measured non-invasively using our multiple-repetition protocol. The novel algorithm was compared to fitting a parabola across the whole dataset to identify how many patients had a plateau region, and whether a higher hemodynamic response was achieved with one method.In 9/82 patients, the restricted parabola algorithm detected that the pattern was not parabolic at longer AV delays. For these patients, the optimal AV delay predicted by the restricted parabola algorithm increased SBP by 1.36 mmHg above that predicted by the conventional parabolic algorithm (95% confidence interval: 0.65 to 2.07 mmHg, p-value = 0.002).AV optima selected using our novel restricted parabola algorithm give a greater improvement in acute hemodynamics than fitting a parabola across all tested AV delays. Such an algorithm may assist the development of automated methods for biventricular pacemaker optimisation.
Nonlinear Gompertz Curve Models of Achievement Gaps in Mathematics and Reading
Cameron, Claire E.; Grimm, Kevin J.; Steele, Joel S.; Castro-Schilo, Laura; Grissmer, David W.
2015-01-01
This study examined achievement trajectories in mathematics and reading from school entry through the end of middle school with linear and nonlinear growth curves in 2 large longitudinal data sets (National Longitudinal Study of Youth--Children and Young Adults and Early Childhood Longitudinal Study--Kindergarten Cohort [ECLS-K]). The S-shaped…
Flow-Induced Vibration of A Nonlinearly Restrained Curved Pipe Conveying Fluid
Institute of Scientific and Technical Information of China (English)
王琳; 倪樵; 黄玉盈
2004-01-01
Investigated in this study is the flow-induced vibration of a nonlinearly restrained curved pipe conveying fluid. The nonlinear equation of motion is derived by equilibrium of forces on microelement of the system under consideration. The spatial coordinate of the system is discretized by DQM (differential quadrature method). On the basis of the boundary conditions, the dynamic equation is solved by the Newton-Raphson iteration method. The numerical solutions reveal several complex dynamic motions for the variation of the fluid velocity parameter, such as limit cycle motion, buckling and so on. The result obtained also shows that the sub parameter regions corresponding to the several motions may change with the variation of some parameters of the curved pipe. The present study supplies a new reference for investigating the nonlinear dynamic response of some other structures.
Directory of Open Access Journals (Sweden)
Bo You
2015-01-01
Full Text Available In order to predict pressing quality of precision press-fit assembly, press-fit curves and maximum press-mounting force of press-fit assemblies were investigated by finite element analysis (FEA. The analysis was based on a 3D Solidworks model using the real dimensions of the microparts and the subsequent FEA model that was built using ANSYS Workbench. The press-fit process could thus be simulated on the basis of static structure analysis. To verify the FEA results, experiments were carried out using a press-mounting apparatus. The results show that the press-fit curves obtained by FEA agree closely with the curves obtained using the experimental method. In addition, the maximum press-mounting force calculated by FEA agrees with that obtained by the experimental method, with the maximum deviation being 4.6%, a value that can be tolerated. The comparison shows that the press-fit curve and max press-mounting force calculated by FEA can be used for predicting the pressing quality during precision press-fit assembly.
Duc, Nguyen Dinh; Quan, Tran Quoc
2012-09-01
An analytical investigation into the nonlinear response of thick functionally graded double-curved shallow panels resting on elastic foundations and subjected to thermal and thermomechanical loads is presented. Young's modulus and Poisson's ratio are both graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of constituents. All formulations are based on the classical shell theory with account of geometrical nonlinearity and initial geometrical imperfection in the cases of Pasternak-type elastic foundations. By applying the Galerkin method, explicit relations for the thermal load-deflection curves of simply supported curved panels are found. The effects of material and geometrical properties and foundation stiffness on the buckling and postbuckling load-carrying capacity of the panels in thermal environments are analyzed and discussed.
A PID Positioning Controller with a Curve Fitting Model Based on RFID Technology
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Young-Long Chen
2013-04-01
Full Text Available The global positioning system (GPS is an important research topic to solve outdoor positioning problems, but GPS is unable to locate objects accurately and precisely indoors. Some available systems apply ultrasound or optical tracking. This paper presents an efficient proportional-integral-derivative (PID controller with curve fitting model for mobile robot localization and position estimation which adopts passive radio frequency identification (RFID tags in a space. This scheme is based on a mobile robot carries an RFID reader module which reads the installed low-cost passive tags under the floor in a grid-like pattern. The PID controllers increase the efficiency of captured RFID tags and the curve fitting model is used to systematically identify the revolutions per minute (RPM of the motor. We control and monitor the position of the robot from a remote location through a mobile phone via Wi-Fi and Bluetooth network. Experiment results present that the number of captured RFID tags of our proposed scheme outperforms that of the previous scheme.
Directory of Open Access Journals (Sweden)
Miguel Angel Merlos Rodrigo
2017-03-01
Full Text Available The translation of metallothioneins (MTs is one of the defense strategies by which organisms protect themselves from metal-induced toxicity. MTs belong to a family of proteins comprising MT-1, MT-2, MT-3, and MT-4 classes, with multiple isoforms within each class. The main aim of this study was to determine the behavior of MT in dependence on various externally modelled environments, using electrochemistry. In our study, the mass distribution of MTs was characterized using MALDI-TOF. After that, adsorptive transfer stripping technique with differential pulse voltammetry was selected for optimization of electrochemical detection of MTs with regard to accumulation time and pH effects. Our results show that utilization of 0.5 M NaCl, pH 6.4, as the supporting electrolyte provides a highly complicated fingerprint, showing a number of non-resolved voltammograms. Hence, we further resolved the voltammograms exhibiting the broad and overlapping signals using curve fitting. The separated signals were assigned to the electrochemical responses of several MT complexes with zinc(II, cadmium(II, and copper(II, respectively. Our results show that electrochemistry could serve as a great tool for metalloproteomic applications to determine the ratio of metal ion bonds within the target protein structure, however, it provides highly complicated signals, which require further resolution using a proper statistical method, such as curve fitting.
A PID Positioning Controller with a Curve Fitting Model Based on RFID Technology
Directory of Open Access Journals (Sweden)
Young-Long Chen
2013-03-01
Full Text Available The global positioning system (GPS is an important research topic to solve outdoor positioning problems, but GPSis unable to locate objects accurately and precisely indoors. Some available systems apply ultrasound or opticaltracking. This paper presents an efficient proportional-integral-derivative (PID controller with curve fitting model formobile robot localization and position estimation which adopts passive radio frequency identification (RFID tags ina space. This scheme is based on a mobile robot carries an RFID reader module which reads the installed low-costpassive tags under the floor in a grid-like pattern. The PID controllers increase the efficiency of captured RFID tagsand the curve fitting model is used to systematically identify the revolutions per minute (RPM of the motor. Wecontrol and monitor the position of the robot from a remote location through a mobile phone via Wi-Fi and Bluetoothnetwork. Experiment results present that the number of captured RFID tags of our proposed scheme outperformsthat of the previous scheme.
Merlos Rodrigo, Miguel Angel; Molina-López, Jorge; Jimenez Jimenez, Ana Maria; Planells Del Pozo, Elena; Adam, Pavlina; Eckschlager, Tomas; Zitka, Ondrej; Richtera, Lukas; Adam, Vojtech
2017-01-01
The translation of metallothioneins (MTs) is one of the defense strategies by which organisms protect themselves from metal-induced toxicity. MTs belong to a family of proteins comprising MT-1, MT-2, MT-3, and MT-4 classes, with multiple isoforms within each class. The main aim of this study was to determine the behavior of MT in dependence on various externally modelled environments, using electrochemistry. In our study, the mass distribution of MTs was characterized using MALDI-TOF. After that, adsorptive transfer stripping technique with differential pulse voltammetry was selected for optimization of electrochemical detection of MTs with regard to accumulation time and pH effects. Our results show that utilization of 0.5 M NaCl, pH 6.4, as the supporting electrolyte provides a highly complicated fingerprint, showing a number of non-resolved voltammograms. Hence, we further resolved the voltammograms exhibiting the broad and overlapping signals using curve fitting. The separated signals were assigned to the electrochemical responses of several MT complexes with zinc(II), cadmium(II), and copper(II), respectively. Our results show that electrochemistry could serve as a great tool for metalloproteomic applications to determine the ratio of metal ion bonds within the target protein structure, however, it provides highly complicated signals, which require further resolution using a proper statistical method, such as curve fitting. PMID:28287470
SiFTO: An Empirical Method for Fitting SNe Ia Light Curves
Conley, A; Hsiao, E Y; Guy, J; Astier, Pierre; Balam, D; Balland, C; Basa, S; Carlberg, R G; Fouchez, D; Hardin, D; Howell, D A; Hook, I M; Pain, R; Perrett, K; Pritchet, C J; Regnault, N
2008-01-01
We present SiFTO, a new empirical method for modeling type Ia supernovae (SNe Ia) light curves by manipulating a spectral template. We make use of high-redshift SN observations when training the model, allowing us to extend it bluer than rest frame U. This increases the utility of our high-redshift SN observations by allowing us to use more of the available data. We find that when the shape of the light curve is described using a stretch prescription, applying the same stretch at all wavelengths is not an adequate description. SiFTO therefore uses a generalization of stretch which applies different stretch factors as a function of both the wavelength of the observed filter and the stretch in the rest-frame B band. We compare SiFTO to other published light-curve models by applying them to the same set of SN photometry, and demonstrate that SiFTO and SALT2 perform better than the alternatives when judged by the scatter around the best fit luminosity distance relationship. We further demonstrate that when SiFTO ...
Directory of Open Access Journals (Sweden)
Juliana C. Ferreira
2011-01-01
Full Text Available OBJECTIVE: Respiratory pressure-volume curves fitted to exponential equations have been used to assess disease severity and prognosis in spontaneously breathing patients with idiopathic pulmonary fibrosis. Sigmoidal equations have been used to fit pressure-volume curves for mechanically ventilated patients but not for idiopathic pulmonary fibrosis patients. We compared a sigmoidal model and an exponential model to fit pressure-volume curves from mechanically ventilated patients with idiopathic pulmonary fibrosis. METHODS: Six idiopathic pulmonary fibrosis patients and five controls underwent inflation pressure-volume curves using the constant-flow technique during general anesthesia prior to open lung biopsy or thymectomy. We identified the lower and upper inflection points and fit the curves with an exponential equation, V = A-B.e-k.P, and a sigmoid equation, V = a+b/(1+e-(P-c/d. RESULTS: The mean lower inflection point for idiopathic pulmonary fibrosis patients was significantly higher (10.5 ± 5.7 cm H2O than that of controls (3.6 ± 2.4 cm H2O. The sigmoidal equation fit the pressure-volume curves of the fibrotic and control patients well, but the exponential equation fit the data well only when points below 50% of the inspiratory capacity were excluded. CONCLUSION: The elevated lower inflection point and the sigmoidal shape of the pressure-volume curves suggest that respiratory system compliance is decreased close to end-expiratory lung volume in idiopathic pulmonary fibrosis patients under general anesthesia and mechanical ventilation. The sigmoidal fit was superior to the exponential fit for inflation pressure-volume curves of anesthetized patients with idiopathic pulmonary fibrosis and could be useful for guiding mechanical ventilation during general anesthesia in this condition.
A theoretical and experimental study on geometric nonlinearity of initially curved cantilever beams
Directory of Open Access Journals (Sweden)
Sushanta Ghuku
2016-03-01
Full Text Available This paper presents a theoretical and experimental study on large deflection behavior of initially curved cantilever beams subjected to various types of loadings. The physical system as a straight cantilever beam subjected to a tip concentrated load is considered in this study. Nonlinear differential equations are obtained for large deflection analysis of such a straight cantilever beam, and this problem is known to involve geometrical nonlinearity. The equations are solved numerically with the help of MATLAB® computational platform to get deflection profiles of the concerned problem. These results are imposed subsequently on the center line of an initially curved beam to get theoretical load-deflection behavior of curved beam problems. To verify the theoretical model, experiment is carried out with the master leaf of a leaf spring bundle by modeling it as an initially curved cantilever beam. The effects of initial clamping and geometry variations in the eye-region are observed from experimental investigation which is commonly neglected in the mathematical formulation. Comparisons of the theoretical results with the experimental results are quite good, but the avenues for further improvement are also reported. The proposed approach is further extended to study large deflection behavior of an initially curved cantilever beam subjected to distributed and combined load. These results are successfully validated with existing results for straight beams and some new results are furnished for initially curved cantilever beams.
Energy Technology Data Exchange (ETDEWEB)
Cardoso, Vanderlei
2002-07-01
The present work describes a few methodologies developed for fitting efficiency curves obtained by means of a HPGe gamma-ray spectrometer. The interpolated values were determined by simple polynomial fitting and polynomial fitting between the ratio of experimental peak efficiency and total efficiency, calculated by Monte Carlo technique, as a function of gamma-ray energy. Moreover, non-linear fitting has been performed using a segmented polynomial function and applying the Gauss-Marquardt method. For the peak area obtainment different methodologies were developed in order to estimate the background area under the peak. This information was obtained by numerical integration or by using analytical functions associated to the background. One non-calibrated radioactive source has been included in the curve efficiency in order to provide additional calibration points. As a by-product, it was possible to determine the activity of this non-calibrated source. For all fittings developed in the present work the covariance matrix methodology was used, which is an essential procedure in order to give a complete description of the partial uncertainties involved. (author)
Energy Technology Data Exchange (ETDEWEB)
Sablik, M.J. [Southwest Research Institute, 6220 Culebra Rd, San Antonio, TX 78238-5166 (United States)]. E-mail: msablik@swri.org; Landgraf, F.J.G. [Metallurgy and Mat. Sci. Dept., Escola Politecnica da USP, 05508-970, Sao Paulo, SP (Brazil); Magnabosco, R. [UNIFEI, Sao Bernardo de Campo, SP (Brazil); Fukuhara, M. [Instituto Nacional de Metrologia INMETRO, Duque de Caxias, RJ (Brazil); Campos, M.F. de [Instituto Nacional de Metrologia INMETRO, Duque de Caxias, RJ (Brazil); Machado, R. [Instituto Nacional de Metrologia INMETRO, Duque de Caxias, RJ (Brazil); Missell, F.P. [Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil)
2006-09-15
We report measurements and modelling of magnetic effects due to plastic deformation in 2.2% Si steel, emphasizing new tensile deformation data. The modelling approach is to take the Ludwik law for the strain-hardening stress and use it to compute the dislocation density, which is then used in the computation of magnetic hysteresis. A nonlinear extrapolation is used across the discontinuous yield region to obtain the value of stress at the yield point that is used in fitting Ludwik's law to the mechanical data. The computed magnetic hysteresis exhibits sharp shearing of the loops at small deformation, in agreement with experimental behavior. Magnetic hysteresis loss is shown to follow a Ludwik-like dependence on the residual strain, but with a smaller Ludwik exponent than applies for the mechanical behavior.
New Fitting Formula for Cosmic Nonlinear Density Distribution
Shin, Jihye; Kim, Juhan; Pichon, Christophe; Jeong, Donghui; Park, Changbom
2017-07-01
We have measured the probability distribution function (PDF) of a cosmic matter density field from a suite of N-body simulations. We propose the generalized normal distribution of version 2 ({{ N }}{{v}2}) as an alternative fitting formula to the well-known log-normal distribution. We find that {{ N }}{{v}2} provides a significantly better fit than that of the log-normal distribution for all smoothing radii (2, 5, 10, 25 [Mpc h -1]) that we studied. The improvement is substantial in the underdense regions. The development of non-Gaussianities in the cosmic matter density field is captured by continuous evolution of the skewness and shift parameters of the {{ N }}{{v}2} distribution. We present the redshift evolution of these parameters for aforementioned smoothing radii and various background cosmology models. All the PDFs measured from large and high-resolution N-body simulations that we use in this study can be obtained from the web site https://astro.kias.re.kr/jhshin.
Zielesny, Achim
2016-01-01
This successful book provides in its second edition an interactive and illustrative guide from two-dimensional curve fitting to multidimensional clustering and machine learning with neural networks or support vector machines. Along the way topics like mathematical optimization or evolutionary algorithms are touched. All concepts and ideas are outlined in a clear cut manner with graphically depicted plausibility arguments and a little elementary mathematics. The major topics are extensively outlined with exploratory examples and applications. The primary goal is to be as illustrative as possible without hiding problems and pitfalls but to address them. The character of an illustrative cookbook is complemented with specific sections that address more fundamental questions like the relation between machine learning and human intelligence. All topics are completely demonstrated with the computing platform Mathematica and the Computational Intelligence Packages (CIP), a high-level function library developed with M...
A curve fitting method for extrinsic camera calibration from a single image of a cylindrical object
Winkler, A. W.; Zagar, B. G.
2013-08-01
An important step in the process of optical steel coil quality assurance is to measure the proportions of width and radius of steel coils as well as the relative position and orientation of the camera. This work attempts to estimate these extrinsic parameters from single images by using the cylindrical coil itself as the calibration target. Therefore, an adaptive least-squares algorithm is applied to fit parametrized curves to the detected true coil outline in the acquisition. The employed model allows for strictly separating the intrinsic and the extrinsic parameters. Thus, the intrinsic camera parameters can be calibrated beforehand using available calibration software. Furthermore, a way to segment the true coil outline in the acquired images is motivated. The proposed optimization method yields highly accurate results and can be generalized even to measure other solids which cannot be characterized by the identification of simple geometric primitives.
Marconi, M.; Molinaro, R.; Ripepi, V.; Cioni, M.-R. L.; Clementini, G.; Moretti, M. I.; Ragosta, F.; de Grijs, R.; Groenewegen, M. A. T.; Ivanov, V. D.
2017-04-01
We present the results of the χ2 minimization model fitting technique applied to optical and near-infrared photometric and radial velocity data for a sample of nine fundamental and three first overtone classical Cepheids in the Small Magellanic Cloud (SMC). The near-infrared photometry (JK filters) was obtained by the European Southern Observatory (ESO) public survey 'VISTA near-infrared Y, J, Ks survey of the Magellanic Clouds system' (VMC). For each pulsator, isoperiodic model sequences have been computed by adopting a non-linear convective hydrodynamical code in order to reproduce the multifilter light and (when available) radial velocity curve amplitudes and morphological details. The inferred individual distances provide an intrinsic mean value for the SMC distance modulus of 19.01 mag and a standard deviation of 0.08 mag, in agreement with the literature. Moreover, the intrinsic masses and luminosities of the best-fitting model show that all these pulsators are brighter than the canonical evolutionary mass-luminosity relation (MLR), suggesting a significant efficiency of core overshooting and/or mass-loss. Assuming that the inferred deviation from the canonical MLR is only due to mass-loss, we derive the expected distribution of percentage mass-loss as a function of both the pulsation period and the canonical stellar mass. Finally, a good agreement is found between the predicted mean radii and current period-radius (PR) relations in the SMC available in the literature. The results of this investigation support the predictive capabilities of the adopted theoretical scenario and pave the way for the application to other extensive data bases at various chemical compositions, including the VMC Large Magellanic Cloud pulsators and Galactic Cepheids with Gaia parallaxes.
Energy Technology Data Exchange (ETDEWEB)
Hussein, Rania [DigiPen Institute of Technology, Department of Computer Engineering, Redmond, WA (United States); McKenzie, Frederic D. [Old Dominion University, Department of Electrical and Computer Engineering, Norfolk, VA (United States)
2007-12-15
To obtain an accurate assessment of the percentage and depth of extra-capsular soft tissue removed with the prostate by the various surgical techniques in order to help surgeons in determining the appropriateness of different surgical approaches. This can be enhanced by an accurate and automated means of identifying the prostate gland contour. To facilitate 3D reconstruction and, ultimately, more accurate analyses, it is essential for us to identify the capsule boundary that separates the prostate gland tissue from its extra-capsular tissue. However, the capsule is sometimes unrecognizable due to the naturally occurring intrusion of muscle and connective tissue into the prostate gland. At these regions where the capsule disappears, its contour can be arbitrarily created with a continuing contour line based on the natural shape of the prostate. We utilize an algorithm based on a least squares curve fitting technique that uses a prostate shape equation to merge previously detected capsule parts with the shape equation to produce an approximated curve that represents the prostate capsule. We have tested our algorithm using three different shapes on 13 histologic prostate slices that are cut at different locations from the apex. The best result shows a 90% average contour match when compared to pathologist-drawn contours. We believe that automatically identifying histologic prostate contours will lead to increased objective analyses of surgical margins and extracapsular spread of cancer. Our results show that this is achievable. (orig.)
Testing the Nonlinearity of the Phillips Curve. Implications for Monetary Policy
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Georgiana BALABAN
2010-04-01
Full Text Available This paper studies the nonlinearity of the Phillips Curve and its implications for monetary policy. To investigate the trade-off between output gap and inflation volatility we used a backward-looking model type. The data for our empirical analysis is obtained from the Area Wide Model (AWM Database (from 1970 to 2008 for Euro area and National Institute of Statistics (from 2000 to 2009 for Romania and has quarterly frequency. The results of econometric tests indicate a significant estimated coefficient of the output gap for Romania, compared with the Eurozone; we find no significant evidence of nonlinearity of the Phillips curve in the European Monetary Union. This suggests that the optimal choice for European Central Bank should be a fixed inflation targeting, while the National Bank of Romania's monetary policy strategy should aim a flexible inflation targeting.
The Nonlinearity of the New Keynesian Phillips Curve: The Case of Tunisia
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Imen Kobbi
2017-07-01
Full Text Available This article seeks to check the nonlinearity of the Phillips curve in Tunisia for the 1993–2012 period, relying on a hybrid new Keynesian Phillips curve modeled via a Logistic Smooth Transition Regression (LSTR model with endogenous variables. We estimate this model using the nonlinear instrumental variables. The empirical results corroborate the new Keynesian assumption ofprice rigidity and show that the response of inflation to the output gap tends to be significant only if the inflation rate tends to be relatively high and exceeds a certain threshold. For a low inflation rate, the price rigidity dominates. This result is particularly evident in Tunisia, especially for the years following the 2011 revolution during which the elasticity of inflation rate to an excess demand has become highly important and the inflation rate experienced record levels.
Ahearn, T S; Staff, R T; Redpath, T W; Semple, S I K
2005-05-07
The use of curve-fitting and compartmental modelling for calculating physiological parameters from measured data has increased in popularity in recent years. Finding the 'best fit' of a model to data involves the minimization of a merit function. An example of a merit function is the sum of the squares of the differences between the data points and the model estimated points. This is facilitated by curve-fitting algorithms. Two curve-fitting methods, Levenberg-Marquardt and MINPACK-1, are investigated with respect to the search start points that they require and the accuracy of the returned fits. We have simulated one million dynamic contrast enhanced MRI curves using a range of parameters and investigated the use of single and multiple search starting points. We found that both algorithms, when used with a single starting point, return unreliable fits. When multiple start points are used, we found that both algorithms returned reliable parameters. However the MINPACK-1 method generally outperformed the Levenberg-Marquardt method. We conclude that the use of a single starting point when fitting compartmental modelling data such as this produces unsafe results and we recommend the use of multiple start points in order to find the global minima.
Tasel, Serdar F.; Hassanpour, Reza; Mumcuoglu, Erkan U.; Perkins, Guy C.; Martone, Maryann
2014-03-01
Mitochondria are sub-cellular components which are mainly responsible for synthesis of adenosine tri-phosphate (ATP) and involved in the regulation of several cellular activities such as apoptosis. The relation between some common diseases of aging and morphological structure of mitochondria is gaining strength by an increasing number of studies. Electron microscope tomography (EMT) provides high-resolution images of the 3D structure and internal arrangement of mitochondria. Studies that aim to reveal the correlation between mitochondrial structure and its function require the aid of special software tools for manual segmentation of mitochondria from EMT images. Automated detection and segmentation of mitochondria is a challenging problem due to the variety of mitochondrial structures, the presence of noise, artifacts and other sub-cellular structures. Segmentation methods reported in the literature require human interaction to initialize the algorithms. In our previous study, we focused on 2D detection and segmentation of mitochondria using an ellipse detection method. In this study, we propose a new approach for automatic detection of mitochondria from EMT images. First, a preprocessing step was applied in order to reduce the effect of nonmitochondrial sub-cellular structures. Then, a curve fitting approach was presented using a Hessian-based ridge detector to extract membrane-like structures and a curve-growing scheme. Finally, an automatic algorithm was employed to detect mitochondria which are represented by a subset of the detected curves. The results show that the proposed method is more robust in detection of mitochondria in consecutive EMT slices as compared with our previous automatic method.
Review of curve-fitting error criteria for solar-cell I-V characteristics
Energy Technology Data Exchange (ETDEWEB)
Phang, J.C.H.; Chan, D.S.H.
1986-07-01
Various methods for recovering solar cell lumped-circuit model parameters from experimental characteristics are briefly reviewed. The advantages of extracting parameters from illuminated characteristics are highlighted. These include the availability of accurate analytical expressions developed recently. A commonly used method of parameter recovery by curve fitting minimises sigma which is defined as the r.m.s. of the relative current errors between the experimental and theoretical characteristics. This method is demonstrated to be unreliable when used with characteristics collected by linear analogue to digital systems, or which have certain data-point distributions. A more-reliable minimisation criterion epsilon is proposed. epsilon is based on the area difference between the experimental and theoretical characteristics. Computation experiments show that the use of epsilon results in much more accurate parameter recovery for both dark and illuminated characteristics, and that its accuracy is almost independent of data-point distribution. epsilon also provides a good basis for comparing the quality of fit of theoretical models to experimental characteristics.
Analytical Light Curve Models of Super-Luminous Supernvae: chi^2-Minimizations of Parameter Fits
Chatzopoulos, E; Vinko, J; Horvath, Z L; Nagy, A
2013-01-01
We present fits of generalized semi-analytic supernova (SN) light curve (LC) models for a variety of power inputs including Ni-56 and Co-56 radioactive decay, magnetar spin-down, and forward and reverse shock heating due to supernova ejecta-circumstellar matter (CSM) interaction. We apply our models to the observed LCs of the H-rich Super Luminous Supernovae (SLSN-II) SN 2006gy, SN 2006tf, SN 2008am, SN 2008es, CSS100217, the H-poor SLSN-I SN 2005ap, SCP06F6, SN 2007bi, SN 2010gx and SN 2010kd as well as to the interacting SN 2008iy and PTF09uj. Our goal is to determine the dominant mechanism that powers the LCs of these extraordinary events and the physical conditions involved in each case. We also present a comparison of our semi-analytical results with recent results from numerical radiation hydrodynamics calculations in the particular case of SN 2006gy in order to explore the strengths and weaknesses of our models. We find that CS shock heating produced by ejecta-CSM interaction provides a better fit to t...
A QUMOND galactic N-body code I: Poisson solver and rotation curve fitting
Angus, Garry W; Famaey, Benoit; Gentile, Gianfranco; McGaugh, Stacy S; de Blok, W J G
2012-01-01
Here we present a new particle-mesh galactic N-body code that uses the full multigrid algorithm for solving the modified Poisson equation of the Quasi Linear formulation of Modified Newtonian Dynamics (QUMOND). A novel approach for handling the boundary conditions using a refinement strategy is implemented and the accuracy of the code is compared with analytical solutions of Kuzmin disks. We then employ the code to compute the predicted rotation curves for a sample of five spiral galaxies from the THINGS sample. We generated static N-body realisations of the galaxies according to their stellar and gaseous surface densities and allowed their distances, mass-to-light ratios (M/L) and both the stellar and gas scale-heights to vary in order to estimate the best fit parameters. We found that NGC 3621, NGC 3521 and DDO 154 are well fit by MOND using expected values of the distance and M/L. NGC 2403 required a moderately larger $M/L$ than expected and NGC 2903 required a substantially larger value. The surprising re...
Brewick, Patrick T.; Smyth, Andrew W.
2016-12-01
The authors have previously shown that many traditional approaches to operational modal analysis (OMA) struggle to properly identify the modal damping ratios for bridges under traffic loading due to the interference caused by the driving frequencies of the traffic loads. This paper presents a novel methodology for modal parameter estimation in OMA that overcomes the problems presented by driving frequencies and significantly improves the damping estimates. This methodology is based on finding the power spectral density (PSD) of a given modal coordinate, and then dividing the modal PSD into separate regions, left- and right-side spectra. The modal coordinates were found using a blind source separation (BSS) algorithm and a curve-fitting technique was developed that uses optimization to find the modal parameters that best fit each side spectra of the PSD. Specifically, a pattern-search optimization method was combined with a clustering analysis algorithm and together they were employed in a series of stages in order to improve the estimates of the modal damping ratios. This method was used to estimate the damping ratios from a simulated bridge model subjected to moving traffic loads. The results of this method were compared to other established OMA methods, such as Frequency Domain Decomposition (FDD) and BSS methods, and they were found to be more accurate and more reliable, even for modes that had their PSDs distorted or altered by driving frequencies.
Intrinsic localized modes and nonlinear impurity modes in curved Fermi-Pasta-Ulam chain
Indian Academy of Sciences (India)
Ranja Sarkar; Bishwajyoti Dey
2008-06-01
We explore the nature of intrinsic localized modes (ILMs) in a curved FermiPasta-Ulam (FPU) chain and the effects of geometry and second-neighbor interaction on the localization and movability properties of such modes. We determine analytically the structure of the localized modes induced by an isotopic light-mass impurity in this chain. We further demonstrate that a nonlinear impurity mode may be treated as a bound state of an ILM with the impurity.
Tracing Analytic Ray Curves for Light and Sound Propagation in Non-Linear Media.
Mo, Qi; Yeh, Hengchin; Manocha, Dinesh
2016-11-01
The physical world consists of spatially varying media, such as the atmosphere and the ocean, in which light and sound propagates along non-linear trajectories. This presents a challenge to existing ray-tracing based methods, which are widely adopted to simulate propagation due to their efficiency and flexibility, but assume linear rays. We present a novel algorithm that traces analytic ray curves computed from local media gradients, and utilizes the closed-form solutions of both the intersections of the ray curves with planar surfaces, and the travel distance. By constructing an adaptive unstructured mesh, our algorithm is able to model general media profiles that vary in three dimensions with complex boundaries consisting of terrains and other scene objects such as buildings. Our analytic ray curve tracer with the adaptive mesh improves the efficiency considerably over prior methods. We highlight the algorithm's application on simulation of visual and sound propagation in outdoor scenes.
Institute of Scientific and Technical Information of China (English)
DONG Sheng; LI Fengli; JIAO Guiying
2003-01-01
Hydrologic frequency analysis plays an important role in coastal and ocean engineering for structural design and disaster prevention in coastal areas. This paper proposes a Nonlinear Least Squares Method (NLSM), which estimates the three unknown parameters of the Weibull distribution simultaneously by an iteration method. Statistical test shows that the NLSM fits each data sample well. The effects of different parameter-fitting methods, distribution models, and threshold values are also discussed in the statistical analysis of storm set-down elevation. The best-fitting probability distribution is given and the corresponding return values are estimated for engineering design.
Energy Technology Data Exchange (ETDEWEB)
Chatzopoulos, E.; Wheeler, J. Craig; Vinko, J. [Department of Astronomy, University of Texas at Austin, Austin, TX (United States); Horvath, Z. L.; Nagy, A., E-mail: manolis@astro.as.utexas.edu [Department of Optics and Quantum Electronics, University of Szeged (Hungary)
2013-08-10
We present fits of generalized semi-analytic supernova (SN) light curve (LC) models for a variety of power inputs including {sup 56}Ni and {sup 56}Co radioactive decay, magnetar spin-down, and forward and reverse shock heating due to supernova ejecta-circumstellar matter (CSM) interaction. We apply our models to the observed LCs of the H-rich superluminous supernovae (SLSN-II) SN 2006gy, SN 2006tf, SN 2008am, SN 2008es, CSS100217, the H-poor SLSN-I SN 2005ap, SCP06F6, SN 2007bi, SN 2010gx, and SN 2010kd, as well as to the interacting SN 2008iy and PTF 09uj. Our goal is to determine the dominant mechanism that powers the LCs of these extraordinary events and the physical conditions involved in each case. We also present a comparison of our semi-analytical results with recent results from numerical radiation hydrodynamics calculations in the particular case of SN 2006gy in order to explore the strengths and weaknesses of our models. We find that CS shock heating produced by ejecta-CSM interaction provides a better fit to the LCs of most of the events we examine. We discuss the possibility that collision of supernova ejecta with hydrogen-deficient CSM accounts for some of the hydrogen-deficient SLSNe (SLSN-I) and may be a plausible explanation for the explosion mechanism of SN 2007bi, the pair-instability supernova candidate. We characterize and discuss issues of parameter degeneracy.
DEFF Research Database (Denmark)
Vang, Jakob Rabjerg; Zhou, Fan; Andreasen, Søren Juhl;
2015-01-01
A high temperature PEM (HTPEM) fuel cell model capable of simulating both steady state and dynamic operation is presented. The purpose is to enable extraction of unknown parameters from sets of impedance spectra and polarisation curves. The model is fitted to two polarisation curves and four...... impedance spectra measured on a Dapozol 77 MEA. The model is capable of achieving good agreement with the recorded curves. Except at OCV, where the voltage is overpredicted, the simulated polarisation curves deviate maximum 3.0% from the measurements. The impedance spectra deviate maximum 3.7%. The fitted...... parameter values are within the range reported in literature. The only exception is the catalyst layer acid content, which is an order of magnitude lower. This may derive from acid migration. The model is used to illustrate the effect of reactant dynamics on the impedance spectrum. The model can aid...
Sub-band denoising and spline curve fitting method for hemodynamic measurement in perfusion MRI
Lin, Hong-Dun; Huang, Hsiao-Ling; Hsu, Yuan-Yu; Chen, Chi-Chen; Chen, Ing-Yi; Wu, Liang-Chi; Liu, Ren-Shyan; Lin, Kang-Ping
2003-05-01
In clinical research, non-invasive MR perfusion imaging is capable of investigating brain perfusion phenomenon via various hemodynamic measurements, such as cerebral blood volume (CBV), cerebral blood flow (CBF), and mean trasnit time (MTT). These hemodynamic parameters are useful in diagnosing brain disorders such as stroke, infarction and periinfarct ischemia by further semi-quantitative analysis. However, the accuracy of quantitative analysis is usually affected by poor signal-to-noise ratio image quality. In this paper, we propose a hemodynamic measurement method based upon sub-band denoising and spline curve fitting processes to improve image quality for better hemodynamic quantitative analysis results. Ten sets of perfusion MRI data and corresponding PET images were used to validate the performance. For quantitative comparison, we evaluate gray/white matter CBF ratio. As a result, the hemodynamic semi-quantitative analysis result of mean gray to white matter CBF ratio is 2.10 +/- 0.34. The evaluated ratio of brain tissues in perfusion MRI is comparable to PET technique is less than 1-% difference in average. Furthermore, the method features excellent noise reduction and boundary preserving in image processing, and short hemodynamic measurement time.
FTIR Study of White and Green Broad Beans Based on Curve-fitting
Institute of Scientific and Technical Information of China (English)
Xiaohua; WANG; Gang; LIU; Quanhong; OU; Xingxiang; ZHAO; Jianming; HAO; Xiangping; ZHOU
2013-01-01
Fourier transform infrared(FTIR)spectroscopy was used to study two kinds of broad beans with white and green cotyledons respectively.The results show that the infrared spectra of the two kinds of broad beans are similar and mainly made up of the absorption bands of protein,and polysaccharides.The second derivative infrared spectra amplified the differences and revealed that there were some obvious differences in the range of 1 800-700 cm-1and 1 200-700 cm-1.Hierarchical cluster analysis(HCA)were used for the discrimination of the two kinds broad beans based on the second derivative spectral data in the region of 1 611-1 100 cm-1,and yielded 88.9%accuracy.The spectra in the range from 1 700 to 1 600 cm-1were used to perform Fourier self-deconvolution and curve fitting,which obtained nine peaks.The ratios of relative areas of the bands atα-helix,β-sheet,β-turn and the unordered structure of protein in white beans were 67.71%,35.6%,35.6%and 21.09%respectively,while the ratios in green beans were 8.02%,31.59%,37.12%and 23.27%respectively.The results indicate that the secondary structure of protein was different in the two kinds of broad beans.
Directory of Open Access Journals (Sweden)
H. Vazquez-Leal
2014-01-01
Full Text Available We present a homotopy continuation method (HCM for finding multiple operating points of nonlinear circuits composed of devices modelled by using piecewise linear (PWL representations. We propose an adaptation of the modified spheres path tracking algorithm to trace the homotopy trajectories of PWL circuits. In order to assess the benefits of this proposal, four nonlinear circuits composed of piecewise linear modelled devices are analysed to determine their multiple operating points. The results show that HCM can find multiple solutions within a single homotopy trajectory. Furthermore, we take advantage of the fact that homotopy trajectories are PWL curves meant to replace the multidimensional interpolation and fine tuning stages of the path tracking algorithm with a simple and highly accurate procedure based on the parametric straight line equation.
Nonlinear Radiative Heat Transfer in Blasius and Sakiadis Flows Over a Curved Surface
Naveed, M.; Abbas, Z.; Sajid, M.
2017-01-01
This study investigates the heat transfer characteristics for Blasius and Sakiadis flows over a curved surface coiled in a circle of radius R having constant curvature. Effects of thermal radiation are also analyzed for nonlinear Rosseland approximation which is valid for all values of the temperature difference between the fluid and the surface. The considered physical situation is represented by a mathematical model using curvilinear coordinates. Similar solutions of the developed partial differential equations are evaluated numerically using a shooting algorithm. Fluid velocity, skin-friction coefficient, temperature and local Nusselt number are the quantities of interest interpreted for the influence of pertinent parameters. A comparison of the present and the published data for a flat surface validates the obtained numerical solution for the curved geometry.
Three-Step Predictor-Corrector of Exponential Fitting Method for Nonlinear Schr(o)dinger Equations
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
We develop the three-step explicit and implicit schemes of exponential fitting methods. We use the threestep explicit exponential fitting scheme to predict an approximation, then use the three-step implicit exponential fitting scheme to correct this prediction. This combination is called the three-step predictor-corrector of exponential fitting method. The three-step predictor-corrector of exponential fitting method is applied to numerically compute the coupled nonlinear Schr(o)dinger equation and the nonlinear Schr(o)dinger equation with varying coefficients. The numerical results show that the scheme is highly accurate.
Nonlinear Analysis and Post-Test Correlation for a Curved PRSEUS Panel
Gould, Kevin; Lovejoy, Andrew E.; Jegley, Dawn; Neal, Albert L.; Linton, Kim, A.; Bergan, Andrew C.; Bakuckas, John G., Jr.
2013-01-01
The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, developed by The Boeing Company, has been extensively studied as part of the National Aeronautics and Space Administration's (NASA s) Environmentally Responsible Aviation (ERA) Program. The PRSEUS concept provides a light-weight alternative to aluminum or traditional composite design concepts and is applicable to traditional-shaped fuselage barrels and wings, as well as advanced configurations such as a hybrid wing body or truss braced wings. Therefore, NASA, the Federal Aviation Administration (FAA) and The Boeing Company partnered in an effort to assess the performance and damage arrestments capabilities of a PRSEUS concept panel using a full-scale curved panel in the FAA Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility. Testing was conducted in the FASTER facility by subjecting the panel to axial tension loads applied to the ends of the panel, internal pressure, and combined axial tension and internal pressure loadings. Additionally, reactive hoop loads were applied to the skin and frames of the panel along its edges. The panel successfully supported the required design loads in the pristine condition and with a severed stiffener. The panel also demonstrated that the PRSEUS concept could arrest the progression of damage including crack arrestment and crack turning. This paper presents the nonlinear post-test analysis and correlation with test results for the curved PRSEUS panel. It is shown that nonlinear analysis can accurately calculate the behavior of a PRSEUS panel under tension, pressure and combined loading conditions.
Directory of Open Access Journals (Sweden)
Iman Eshraghi
2016-09-01
Full Text Available Imperfection sensitivity of large amplitude vibration of curved single-walled carbon nanotubes (SWCNTs is considered in this study. The SWCNT is modeled as a Timoshenko nano-beam and its curved shape is included as an initial geometric imperfection term in the displacement field. Geometric nonlinearities of von Kármán type and nonlocal elasticity theory of Eringen are employed to derive governing equations of motion. Spatial discretization of governing equations and associated boundary conditions is performed using differential quadrature (DQ method and the corresponding nonlinear eigenvalue problem is iteratively solved. Effects of amplitude and location of the geometric imperfection, and the nonlocal small-scale parameter on the nonlinear frequency for various boundary conditions are investigated. The results show that the geometric imperfection and non-locality play a significant role in the nonlinear vibration characteristics of curved SWCNTs.
Indian Academy of Sciences (India)
K. Karami; R. Mohebi
2007-12-01
We use the method introduced by Karami & Mohebi (2007), and Karami & Teimoorinia (2007) which enable us to derive the orbital parameters of the spectroscopic binary stars by the nonlinear least squares of observed . curve fitting (o–c). Using the measured experimental data for radial velocities of the four double-lined spectroscopic binary systems PV Pup, HD 141929, EE Cet and V921 Her, we find both the orbital and the combined spectroscopic elements of these systems. Our numerical results are in good agreement with those obtained using the method of Lehmann-Filhés.
Gálvez, Akemi; Iglesias, Andrés; Cabellos, Luis
2014-01-01
The problem of data fitting is very important in many theoretical and applied fields. In this paper, we consider the problem of optimizing a weighted Bayesian energy functional for data fitting by using global-support approximating curves. By global-support curves we mean curves expressed as a linear combination of basis functions whose support is the whole domain of the problem, as opposed to other common approaches in CAD/CAM and computer graphics driven by piecewise functions (such as B-splines and NURBS) that provide local control of the shape of the curve. Our method applies a powerful nature-inspired metaheuristic algorithm called cuckoo search, introduced recently to solve optimization problems. A major advantage of this method is its simplicity: cuckoo search requires only two parameters, many fewer than other metaheuristic approaches, so the parameter tuning becomes a very simple task. The paper shows that this new approach can be successfully used to solve our optimization problem. To check the performance of our approach, it has been applied to five illustrative examples of different types, including open and closed 2D and 3D curves that exhibit challenging features, such as cusps and self-intersections. Our results show that the method performs pretty well, being able to solve our minimization problem in an astonishingly straightforward way.
Institute of Scientific and Technical Information of China (English)
刘汝宽; 许方雷; 肖志红; 李昌珠; 李辉; 曾凡涛; 叶红齐
2015-01-01
The relationships among compression ratio and stress, compression ratio and residual oil of cake in pressing process of castor beans were studied using the test equipment under different states of oilseeds and ways of pressing manners. The results show that variation of stress increases nonlinearly and residual oil rate decreases with the increase of compression ratio. Lower residual oil of cake was obtained by pressing gently and frequently. Curve fitting on both relationships had been built and parameters for the model were obtained by least square procedure and deepening research on pressing process of the castor beans for castor oil. By assuming that the value of oil production is equivalent to the value of energy consumption, the critical compression ratio of intact seeds is 6.2 while that of crushed seeds is 3.6.
Directory of Open Access Journals (Sweden)
Fabyano Fonseca e Silva
Full Text Available ABSTRACT: Genome association analyses have been successful in identifying quantitative trait loci (QTLs for pig body weights measured at a single age. However, when considering the whole weight trajectories over time in the context of genome association analyses, it is important to look at the markers that affect growth curve parameters. The easiest way to consider them is via the two-step method, in which the growth curve parameters and marker effects are estimated separately, thereby resulting in a reduction of the statistical power and the precision of estimates. One efficient solution is to adopt nonlinear mixed models (NMM, which enables a joint modeling of the individual growth curves and marker effects. Our aim was to propose a genome association analysis for growth curves in pigs based on NMM as well as to compare it with the traditional two-step method. In addition, we also aimed to identify the nearest candidate genes related to significant SNP (single nucleotide polymorphism markers. The NMM presented a higher number of significant SNPs for adult weight (A and maturity rate (K, and provided a direct way to test SNP significance simultaneously for both the A and K parameters. Furthermore, all significant SNPs from the two-step method were also reported in the NMM analysis. The ontology of the three candidate genes (SH3BGRL2, MAPK14, and MYL9 derived from significant SNPs (simultaneously affecting A and K allows us to make inferences with regards to their contribution to the pig growth process in the population studied.
Variational principle and a perturbative solution of non-linear string equations in curved space
Roshchupkin, S N
1999-01-01
String dynamics in a curved space-time is studied on the basis of an action functional including a small parameter of rescaled tension constant. A rescaled slow worldsheet time $T=\\epsilon\\tau$ is introduced, and general covariant non-linear string equation are derived. It is shown that in the first order of an $\\epsilon $-expansion these equations are reduced to the known equation for geodesic derivation but complemented by a string oscillatory term. These equations are solved for the de Sitter and Friedmann -Robertson-Walker spaces. The primary string constraints are found to be split into a chain of perturbative constraints and their conservation and consistency are proved. It is established that in the proposed realization of the perturbative approach the string dynamics in the de Sitter space is stable for a large Hubble constant $H
Seyffert, A S; Harding, A K; Allison, J; Schutte, W D
2016-01-01
Since the launch of the Fermi Large Area Telescope in 2008 the number of known ${\\gamma}$-ray pulsars has increased immensely to over 200, many of which are also visible in the radio and X-ray bands. Seyffert et al. (2011) demonstrated how constraints on the viewing geometries of some of these pulsars could be obtained by comparing their observed radio and ${\\gamma}$-ray light curves by eye to light curves from geometric models. While these constraints compare reasonably well with those yielded by more rigorous single-wavelength approaches, they are still a somewhat subjective representation of how well the models reproduce the observed radio and ${\\gamma}$-ray light curves. Constructing a more rigorous approach is, however, made difficult by the large uncertainties associated with the ${\\gamma}$-ray light curves as compared to those associated with the radio light curves. Naively applying a ${\\chi}^{2}$-like goodness-of-fit test to both bands invariably results in constraints dictated by the radio light curv...
[The Research of Oxygen Measurement by TDLAS Based on Levenberg-Marquardt Nonlinear Fitting].
Yan, Jie; Zhai, Chang; Wang, Xiao-niu; Huang, Wen-ping
2015-06-01
Oxygen concentration is an important monitoring parameter in industrial process. Wavelength modulation spectroscopy of tunable diode laser absorption spectroscopy (TDLAS) was used to measure concentration of oxygen gas in industrial process by online monitoring. In this paper, we use the characteristic absorption peak of Oxygen at 760 nm to measure the oxygen concentration. Because of the strong coherence of laser, the detection sensitivity of TDLAS is severely restricted by optical interference noise. Especially at low concentrations, there is larger error by extraction signal in the absorption peak waveform because of the background fluctuation caused by optical interference. In response to this situation, Levenberg-Marquardt nonlinear fitting algorithm was proposed, and the use of the absorption line-derivative form of Lorenz line to fit the second harmonic signal and to extract the peak amplitude. On the other hand, Levenberg-Marquardt nonlinear fitting method needs a large amount of calculation. In order to develop the TDLAS analyzer can achieve real-time monitoring of the site, we use the C28 series of DSQ for data processing which support floating-point arithmetic, and the instrument achieve real-time monitoring capabilities in industrial process. Experimental results show that the algorithm can effectively extract the absorption peak characteristic value of the 2nd harmonic signal and overcome the background noise, The ratio of calculated by algorithm to actual oxygen concentration is nearly 1.01, the linear error of the concentration measurement is 1.18%.
Nonlinear Free Vibration Analysis of Thin-walled Curved Beam with Non-symmetric Open Cross Section
Institute of Scientific and Technical Information of China (English)
DUAN Hai-juan; SONG Zhen-sen
2008-01-01
A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section. The kinetic and potential energies were derived by the virtual principle. The energy function includes the effect of flexural-torsional coupling, the torsion warping and the shear centre location. For finite element analysis, cubic polynomials were utilized as the shape functions of the two nodal thin-walled curved elements. Each node possesses seven degrees freedom including the warping degree of freedom. The nonlinear eigenvalue problem was solved by the direct iteration technique. The results are compared with those for straight beams as available in the literature. The results for nonlinear free vibration analysis of curved beams for various radii and subtended angle are presented.
De Mello, Fernanda; Oliveira, Carlos A L; Ribeiro, Ricardo P; Resende, Emiko K; Povh, Jayme A; Fornari, Darci C; Barreto, Rogério V; McManus, Concepta; Streit, Danilo
2015-01-01
Was evaluated the pattern of growth among females and males of tambaqui by Gompertz nonlinear regression model. Five traits of economic importance were measured on 145 animals during the three years, totaling 981 morphometric data analyzed. Different curves were adjusted between males and females for body weight, height and head length and only one curve was adjusted to the width and body length. The asymptotic weight (a) and relative growth rate to maturity (k) were different between sexes in animals with ± 5 kg; slaughter weight practiced by a specific niche market, very profitable. However, there was no difference between males and females up to ± 2 kg; slaughter weight established to supply the bigger consumer market. Females showed weight greater than males (± 280 g), which are more suitable for fish farming purposes defined for the niche market to larger animals. In general, males had lower maximum growth rate (8.66 g / day) than females (9.34 g / day), however, reached faster than females, 476 and 486 days growth rate, respectively. The height and length body are the traits that contributed most to the weight at 516 days (P <0.001).
Lin, Ying-Tsong; McMahon, Kara G; Lynch, James F; Siegmann, William L
2013-01-01
The acoustic ducting effect by curved nonlinear gravity waves in shallow water is studied through idealized models in this paper. The internal wave ducts are three-dimensional, bounded vertically by the sea surface and bottom, and horizontally by aligned wavefronts. Both normal mode and parabolic equation methods are taken to analyze the ducted sound field. Two types of horizontal acoustic modes can be found in the curved internal wave duct. One is a whispering-gallery type formed by the sound energy trapped along the outer and concave boundary of the duct, and the other is a fully bouncing type due to continual reflections from boundaries in the duct. The ducting condition depends on both internal-wave and acoustic-source parameters, and a parametric study is conducted to derive a general pattern. The parabolic equation method provides full-field modeling of the sound field, so it includes other acoustic effects caused by internal waves, such as mode coupling/scattering and horizontal Lloyd's mirror interference. Two examples are provided to present internal wave ducts with constant curvature and meandering wavefronts.
Balbuena Ortega, A; Arroyo Carrasco, M L; Méndez Otero, M M; Gayou, V L; Delgado Macuil, R; Martínez Gutiérrez, H; Iturbe Castillo, M D
2014-12-12
In this paper, the nonlinear refractive index of colloidal gold nanoparticles under continuous wave illumination is investigated with the z-scan technique. Gold nanoparticles were synthesized using ascorbic acid as reductant, phosphates as stabilizer and cetyltrimethylammonium chloride (CTAC) as surfactant agent. The nanoparticle size was controlled with the CTAC concentration. Experiments changing incident power and sample concentration were done. The experimental z-scan results were fitted with three models: thermal lens, aberrant thermal lens and the nonlocal model. It is shown that the nonlocal model reproduces with exceptionally good agreement; the obtained experimental behaviour.
DEFF Research Database (Denmark)
Tatu, Aditya Jayant
defined subspace, the N-links bicycle chain space, i.e. the space of curves with equidistant neighboring landmark points. This in itself is a useful shape space for medical image analysis applications. The Histogram of Gradient orientation based features are many in number and are widely used......This thesis deals with two unrelated issues, restricting curve evolution to subspaces and computing image patches in the equivalence class of Histogram of Gradient orientation based features using nonlinear projection methods. Curve evolution is a well known method used in various applications like...... specific requirements like shape priors or a given data model, and due to limitations of the computer, the computed curve evolution forms a path in some finite dimensional subspace of the space of curves. We give methods to restrict the curve evolution to a finite dimensional linear or implicitly defined...
Directory of Open Access Journals (Sweden)
Akemi Gálvez
2014-01-01
for data fitting by using global-support approximating curves. By global-support curves we mean curves expressed as a linear combination of basis functions whose support is the whole domain of the problem, as opposed to other common approaches in CAD/CAM and computer graphics driven by piecewise functions (such as B-splines and NURBS that provide local control of the shape of the curve. Our method applies a powerful nature-inspired metaheuristic algorithm called cuckoo search, introduced recently to solve optimization problems. A major advantage of this method is its simplicity: cuckoo search requires only two parameters, many fewer than other metaheuristic approaches, so the parameter tuning becomes a very simple task. The paper shows that this new approach can be successfully used to solve our optimization problem. To check the performance of our approach, it has been applied to five illustrative examples of different types, including open and closed 2D and 3D curves that exhibit challenging features, such as cusps and self-intersections. Our results show that the method performs pretty well, being able to solve our minimization problem in an astonishingly straightforward way.
Reliability of temperature determination from curve-fitting in multi-wavelength pyrometery
Energy Technology Data Exchange (ETDEWEB)
Ni, P. A.; More, R. M.; Bieniosek, F. M.
2013-08-04
Abstract This paper examines the reliability of a widely used method for temperature determination by multi-wavelength pyrometry. In recent WDM experiments with ion-beam heated metal foils, we found that the statistical quality of the fit to the measured data is not necessarily a measure of the accuracy of the inferred temperature. We found a specific example where a second-best fit leads to a more realistic temperature value. The physics issue is the wavelength-dependent emissivity of the hot surface. We discuss improvements of the multi-frequency pyrometry technique, which will give a more reliable determination of the temperature from emission data.
Ferreira, Abílio G T; Henrique, Douglas S; Vieira, Ricardo A M; Maeda, Emilyn M; Valotto, Altair A
2015-03-01
The objective of this study was to evaluate four mathematical models with regards to their fit to lactation curves of Holstein cows from herds raised in the southwestern region of the state of Parana, Brazil. Initially, 42,281 milk production records from 2005 to 2011 were obtained from "Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH)". Data lacking dates of drying and total milk production at 305 days of lactation were excluded, resulting in a remaining 15,142 records corresponding to 2,441 Holstein cows. Data were sorted according to the parity order (ranging from one to six), and within each parity order the animals were divided into quartiles (Q25%, Q50%, Q75% and Q100%) corresponding to 305-day lactation yield. Within each parity order, for each quartile, four mathematical models were adjusted, two of which were predominantly empirical (Brody and Wood) whereas the other two presented more mechanistic characteristics (models Dijkstra and Pollott). The quality of fit was evaluated by the corrected Akaike information criterion. The Wood model showed the best fit in almost all evaluated situations and, therefore, may be considered as the most suitable model to describe, at least empirically, the lactation curves of Holstein cows raised in Southwestern Parana.
Directory of Open Access Journals (Sweden)
Abílio G.T. Ferreira
2015-03-01
Full Text Available The objective of this study was to evaluate four mathematical models with regards to their fit to lactation curves of Holstein cows from herds raised in the southwestern region of the state of Parana, Brazil. Initially, 42,281 milk production records from 2005 to 2011 were obtained from "Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH". Data lacking dates of drying and total milk production at 305 days of lactation were excluded, resulting in a remaining 15,142 records corresponding to 2,441 Holstein cows. Data were sorted according to the parity order (ranging from one to six, and within each parity order the animals were divided into quartiles (Q25%, Q50%, Q75% and Q100% corresponding to 305-day lactation yield. Within each parity order, for each quartile, four mathematical models were adjusted, two of which were predominantly empirical (Brody and Wood whereas the other two presented more mechanistic characteristics (models Dijkstra and Pollott. The quality of fit was evaluated by the corrected Akaike information criterion. The Wood model showed the best fit in almost all evaluated situations and, therefore, may be considered as the most suitable model to describe, at least empirically, the lactation curves of Holstein cows raised in Southwestern Parana.
Multiperiodicity, modulations and flip-flops in variable star light curves I. Carrier fit method
Pelt, J; Mantere, M J; Tuominen, I
2011-01-01
The light curves of variable stars are commonly described using simple trigonometric models, that make use of the assumption that the model parameters are constant in time. This assumption, however, is often violated, and consequently, time series models with components that vary slowly in time are of great interest. In this paper we introduce a class of data analysis and visualization methods which can be applied in many different contexts of variable star research, for example spotted stars, variables showing the Blazhko effect, and the spin-down of rapid rotators. The methods proposed are of explorative type, and can be of significant aid when performing a more thorough data analysis and interpretation with a more conventional method.Our methods are based on a straightforward decomposition of the input time series into a fast "clocking" periodicity and smooth modulating curves. The fast frequency, referred to as the carrier frequency, can be obtained from earlier observations (for instance in the case of p...
Bayesian fitting of a logistic dose-response curve with numerically derived priors.
Huson, L W; Kinnersley, N
2009-01-01
In this report we describe the Bayesian analysis of a logistic dose-response curve in a Phase I study, and we present two simple and intuitive numerical approaches to construction of prior probability distributions for the model parameters. We combine these priors with the expert prior opinion and compare the results of the analyses with those obtained from the use of alternative prior formulations.
Combining biomarkers linearly and nonlinearly for classification using the area under the ROC curve.
Fong, Youyi; Yin, Shuxin; Huang, Ying
2016-09-20
In biomedical studies, it is often of interest to classify/predict a subject's disease status based on a variety of biomarker measurements. A commonly used classification criterion is based on area under the receiver operating characteristic curve (AUC). Many methods have been proposed to optimize approximated empirical AUC criteria, but there are two limitations to the existing methods. First, most methods are only designed to find the best linear combination of biomarkers, which may not perform well when there is strong nonlinearity in the data. Second, many existing linear combination methods use gradient-based algorithms to find the best marker combination, which often result in suboptimal local solutions. In this paper, we address these two problems by proposing a new kernel-based AUC optimization method called ramp AUC (RAUC). This method approximates the empirical AUC loss function with a ramp function and finds the best combination by a difference of convex functions algorithm. We show that as a linear combination method, RAUC leads to a consistent and asymptotically normal estimator of the linear marker combination when the data are generated from a semiparametric generalized linear model, just as the smoothed AUC method. Through simulation studies and real data examples, we demonstrate that RAUC outperforms smooth AUC in finding the best linear marker combinations, and can successfully capture nonlinear pattern in the data to achieve better classification performance. We illustrate our method with a dataset from a recent HIV vaccine trial. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Equilibrium equations for nonlinear buckling analysis of drill-strings in 3D curved well-bores
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
With the development of drilling technology, the oil/gas well has evolved from its early vertical straight form to the inclined, horizontal, plane curved, or even 3D curved well-bore. Understanding of the buck- ling behavior of a drill-string in a well-bore is crucial for the success of a drilling operation. Therefore, equilibrium equations for analyzing the buckling behavior of a drill-string in a 3D curved well-bore are required. Based on Love’s equilibrium equations for a curved and twisted rod in space, a set of equi- librium equations for the nonlinear buckling analysis of a drill-string in a 3D curved well-bore are de- rived by introducing a radial constraint of the well-bore. The proposed formulae can account for the well curvature and tortuosity. Thus, it can be used to analyze the buckling behaviors of a drill-string constrained in a well-bore and subjected to axial compression, torsion at its upper end, and gravity simultaneously. It is worth noting that the existing equations in the literature for a drill-string in a straight and plane curved well-bore with a constant curvature are a special case of the proposed model. Thus, the present model can provide a theoretical basis for the nonlinear buckling analysis of a drill-string constrained in a 3D curved well-bore.
Equilibrium equations for nonlinear buckling analysis of drill-strings in 3D curved well-bores
Institute of Scientific and Technical Information of China (English)
TAN MeiLan; GAN LiFei
2009-01-01
With the development of drilling technology, the oil/gas well has evolved from its early vertical straight form to the inclined, horizontal, plane curved, or even 3D curved well-bore. Understanding of the buck-ling behavior of a drill-string in a well-bore is crucial for the success of a drilling operation. Therefore, equilibrium equations for analyzing the buckling behavior of a drill-string in a 3D curved well-bore are required. Based on Love's equilibrium equations for a curved and twisted rod in space, s set of equi-librium equations for the nonlinear buckling analysis of a drill-string in a 3D curved well-bore are de-rived by introducing a radial constraint of the well-bore. The proposed formulae can account for the well curvature and tortuosity. Thus, it can be used to analyze the buckling behaviors of a drill-string constrained in a well-bore and subjected to axial compression, torsion at its upper end, and gravity simultaneously. It is worth noting that the existing equations in the literature for a drill-string in a straight and plane curved well-bore with a constant curvature are a special case of the proposed model. Thus, the present model can provide s theoretical basis for the nonlinear buckling analysis of a drill-string constrained in a 3D curved well-bore.
Martí-Vidal, I.; Marcaide, J. M.; Alberdi, A.; Guirado, J. C.; Pérez-Torres, M. A.; Ros, E.
2011-02-01
We report on a simultaneous modelling of the expansion and radio light curves of the supernova SN1993J. We developed a simulation code capable of generating synthetic expansion and radio light curves of supernovae by taking into consideration the evolution of the expanding shock, magnetic fields, and relativistic electrons, as well as the finite sensitivity of the interferometric arrays used in the observations. Our software successfully fits all the available radio data of SN 1993J with a standard emission model for supernovae, which is extended with some physical considerations, such as an evolution in the opacity of the ejecta material, a radial decline in the magnetic fields within the radiating region, and a changing radial density profile for the circumstellar medium starting from day 3100 after the explosion.
Marti-Vidal, I; Alberdi, A; Guirado, J C; Perez-Torres, M A; Ros, E
2010-01-01
We report on a simultaneous modelling of the expansion and radio light curves of SN1993J. We have developed a simulation code capable of generating synthetic expansion and radio light curves of supernovae by taking into consideration the evolution of the expanding shock, magnetic fields, and relativistic electrons, as well as the finite sensitivity of the interferometric arrays used in the observations. Our software successfully fits all the available radio data of SN 1993J with an standard emission model for supernovae extended with some physical considerations, as an evolution in the opacity of the ejecta material, a radial drop of the magnetic fields inside the radiating region, and a changing radial density profile of the circumstellar medium beyond day 3100 after explosion.
Fukuda, David H; Smith, Abbie E; Kendall, Kristina L; Cramer, Joel T; Stout, Jeffrey R
2012-02-01
The purpose of this study was to evaluate the use of critical velocity (CV) and isoperformance curves as an alternative to the Army Physical Fitness Test (APFT) two-mile running test. Seventy-eight men and women (mean +/- SE; age: 22.1 +/- 0.34 years; VO2(MAX): 46.1 +/- 0.82 mL/kg/min) volunteered to participate in this study. A VO2(MAX) test and four treadmill running bouts to exhaustion at varying intensities were completed. The relationship between total distance and time-to-exhaustion was tracked for each exhaustive run to determine CV and anaerobic running capacity. A VO2(MAX) prediction equation (Coefficient of determination: 0.805; Standard error of the estimate: 3.2377 mL/kg/min) was developed using these variables. Isoperformance curves were constructed for men and women to correspond with two-mile run times from APFT standards. Individual CV and anaerobic running capacity values were plotted and compared to isoperformance curves for APFT 2-mile run scores. Fifty-four individuals were determined to receive passing scores from this assessment. Physiological profiles identified from this procedure can be used to assess specific aerobic or anaerobic training needs. With the use of time-to-exhaustion as opposed to a time-trial format used in the two-mile run test, pacing strategies may be limited. The combination of variables from the CV test and isoperformance curves provides an alternative to standardized time-trial testing.
Mead, Alexander; Heymans, Catherine; Joudaki, Shahab; Heavens, Alan
2015-01-01
We present an optimised variant of the halo model, designed to produce accurate matter power spectra well into the non-linear regime for a wide range of cosmological models. To do this, we introduce physically-motivated free parameters into the halo-model formalism and fit these to data from high-resolution N-body simulations. For a variety of $\\Lambda$CDM and $w$CDM models the halo-model power is accurate to $\\simeq 5$ per cent for $k\\leq 10h\\,\\mathrm{Mpc}^{-1}$ and $z\\leq 2$. We compare our results with recent revisions of the popular HALOFIT model and show that our predictions are more accurate. An advantage of our new halo model is that it can be adapted to account for the effects of baryonic feedback on the power spectrum. We demonstrate this by fitting the halo model to power spectra from the OWLS hydrodynamical simulation suite via parameters that govern halo internal structure. We are able to fit all feedback models investigated at the 5 per cent level using only two free parameters, and we place limi...
Duc, Nguyen Dinh; Quan, Tran Quoc
2013-11-01
The nonlinear response of buckling and posbuckling of imperfect thin functionally graded doubly curved thin shallow shells resting on elastic foundations and subjected to some mechanical loads is investigated analytically. The elastic moduli of materials, Young's modulus, and Poisson ratio are all graded in the shell thickness direction according to a simple power-law in terms of volume fractions of constituents. All formulations are based on the classical theory of shells with account of geometrical nonlinearity, an initial geometrical imperfection, and a Pasternak-type elastic foundation. By employing the Galerkin method, explicit relations for the load-deflection curves of simply supported doubly curved shallow FGM shells are determined. The effects of material and geometrical properties, foundation stiffness, and imperfection of shells on the buckling and postbuckling loadcarrying capacity of spherical and cylindrical shallow FGM shells are analyzed and discussed.
Institute of Scientific and Technical Information of China (English)
张秀琦; 郑建斌; 高鸿
2001-01-01
Fourier self-deconvolution was the most effective technique in resolving overlapping bands, in which deconvolution function results in deconvolution and apodization smoothes the magnified noise. Yet, the choice of the original half-width of each component and breaking point for truncation is often very subjective. In this paper, the method of combined wavelet transform with curve fitting was described with the advantages of an enhancement of signal to noise ratio as well as the improved fitting condition, and was applied to objective optimization of the o riginal half-widths of components in unresolved bands for Fourier self-deconvolution. Again, a noise was separated from a noisy signal by wavelet transform,therefore, the breaking point of apodization function can be determined directly in frequency domain. Accordingly, some artifacts in Fourier self-deconvolution were minimized significantly.
The Carnegie Supernova Project: Light-curve Fitting with SNooPy
Burns, Christopher R.; Stritzinger, Maximilian; Phillips, M. M.; Kattner, ShiAnne; Persson, S. E.; Madore, Barry F.; Freedman, Wendy L.; Boldt, Luis; Campillay, Abdo; Contreras, Carlos; Folatelli, Gaston; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Salgado, Francisco; Suntzeff, Nicholas B.
2011-01-01
In providing an independent measure of the expansion history of the universe, the Carnegie Supernova Project (CSP) has observed 71 high-z Type Ia supernovae (SNe Ia) in the near-infrared bands Y and J. These can be used to construct rest-frame i-band light curves which, when compared to a low-z sample, yield distance moduli that are less sensitive to extinction and/or decline-rate corrections than in the optical. However, working with NIR observed and i-band rest-frame photometry presents unique challenges and has necessitated the development of a new set of observational tools in order to reduce and analyze both the low-z and high-z CSP sample. We present in this paper the methods used to generate uBVgriYJH light-curve templates based on a sample of 24 high-quality low-z CSP SNe. We also present two methods for determining the distances to the hosts of SN Ia events. A larger sample of 30 low-z SNe Ia in the Hubble flow is used to calibrate these methods. We then apply the method and derive distances to seven galaxies that are so nearby that their motions are not dominated by the Hubble flow.
The Carnegie Supernova Project: Light Curve Fitting with SNooPy
Burns, Christopher R; Phillips, M M; Katner, ShiAnne; Persson, S E; Madore, Barry F; Freedman, Wendy L; Boldt, Luis; Campillay, Abdo; Contreras, Carlos; Folatelli, Gaston; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Salgado, Francisco; Suntzeff, Nicholas B
2010-01-01
In providing an independent measure of the expansion history of the Universe, the Carnegie Supernova Project (CSP) has observed 71 high-z Type Ia supernovae (SNe Ia) in the near-infrared bands Y and J. These can be used to construct rest-frame i-band light curves which, when compared to a low-z sample, yield distance moduli that are less sensitive to extinction and/or decline-rate corrections than in the optical. However, working with NIR observed and i-band rest frame photometry presents unique challenges and has necessitated the development of a new set of observational tools in order to reduce and analyze both the low-z and high-z CSP sample. We present in this paper the methods used to generate uBVgriYJH light-curve templates based on a sample of 24 high-quality low-z CSP SNe. We also present two methods for determining the distances to the hosts of SN Ia events. A larger sample of 30 low-z SNe Ia in the Hubble Flow are used to calibrate these methods. We then apply the method and derive distances to seve...
Nair, S P; Righetti, R
2015-05-07
Recent elastography techniques focus on imaging information on properties of materials which can be modeled as viscoelastic or poroelastic. These techniques often require the fitting of temporal strain data, acquired from either a creep or stress-relaxation experiment to a mathematical model using least square error (LSE) parameter estimation. It is known that the strain versus time relationships for tissues undergoing creep compression have a non-linear relationship. In non-linear cases, devising a measure of estimate reliability can be challenging. In this article, we have developed and tested a method to provide non linear LSE parameter estimate reliability: which we called Resimulation of Noise (RoN). RoN provides a measure of reliability by estimating the spread of parameter estimates from a single experiment realization. We have tested RoN specifically for the case of axial strain time constant parameter estimation in poroelastic media. Our tests show that the RoN estimated precision has a linear relationship to the actual precision of the LSE estimator. We have also compared results from the RoN derived measure of reliability against a commonly used reliability measure: the correlation coefficient (CorrCoeff). Our results show that CorrCoeff is a poor measure of estimate reliability for non-linear LSE parameter estimation. While the RoN is specifically tested only for axial strain time constant imaging, a general algorithm is provided for use in all LSE parameter estimation.
The Contraction-Expansion Algorithm and Its Use in Fitting Nonlinear Equation
Institute of Scientific and Technical Information of China (English)
Gu Shiliang; Hui Dafeng; Bian Aihua
1998-01-01
A new optimization method, contraction-expansion algorithm, is developed and applied to fit nonlinear equations. Five points with equal distance are allocated in the given initial intervals, then the algorithm searches for the points of better objective function one round after another, with contracting and expanding intervals alternatively.The step length (l), a critical factor to optimal solution, is determined and adjusted by feedback information of the searching process. The experiments with number of simulated and real data sets show that the new algorithm is much easier to the optimization than other methods. The algorithm does not need to provide derivatives of the equation.This algorithm can also be used in other optimization problems.
Yukita, Kazuto; Kato, Shinya; Goto, Yasuyuki; Ichiyanagi, Katsuhiro; Kawashima, Yasuhiro
Recently, the independent power producers (IPPs) and the distributed power generations (DGs) are increase on by the electric power system with the power system deregulation. And the power system becomes more complicated. It is necessary to carry out the electric power demand forecasting in order to the power system is operated for the high economical and the high-efficient. For the improvement of electric power demand forecasting, many methods, such as the methods using fuzzy theory, neural network and SDP data, are proposed. In this paper, we proposed the method using STROGANOFF (STructured Re-presentation on Genetic Algorithms for Non-linear Function Fitting) that approximate the value of predictive to the future data by the past data is obtained. Also, the weather condition was considered for the forecasting that is improvement, and the daily peak load forecasting in next day on Chubu district in Japan was carried out, and the effectiveness of proposed method was examined.
Directory of Open Access Journals (Sweden)
Jorge Luis Ferreira
2011-09-01
.80kg and 0.004 dia-1; 337.60kg and 0.005 dia-1; and 309.60kg and 0,008 dia-1 for Brody, Von Bertalanffy, Gompertz and Logistic nonlinear models, respectively. The data adjustment for weight-age of the animal provides information describing the growth curve and the future prognostic for animals managed under the same environmental situation. The properties of four nonlinear models were discussed concerning its applications in the fitting of growth curves in Nellore cattle production. In the period analyzed, Von Bertalanffy nonlinear model was indicated to estimate the body weight of Nellore cattle from Northern Brazil.
Navascues, M. A.; Sebastian, M. V.
Fractal interpolants of Barnsley are defined for any continuous function defined on a real compact interval. The uniform distance between the function and its approximant is bounded in terms of the vertical scale factors. As a general result, the density of the affine fractal interpolation functions of Barnsley in the space of continuous functions in a compact interval is proved. A method of data fitting by means of fractal interpolation functions is proposed. The procedure is applied to the quantification of cognitive brain processes. In particular, the increase in the complexity of the electroencephalographic signal produced by the execution of a test of visual attention is studied. The experiment was performed on two types of children: a healthy control group and a set of children diagnosed with an attention deficit disorder.
Institute of Scientific and Technical Information of China (English)
刘俏; 刘立昕; 金子豪; 赵明举; 齐小辉
2013-01-01
反应器停留时间分布的确定是建立反应器流动模型的基础。本文介绍了用 MATLAB 的 Curve Fitting Toolbox 计算反应器停留时间分布的方法。通过在图形界面下导入数据及平滑处理、采用平滑样条拟合数据以及数值积分等操作，确定了反应器停留时间分布的特征值，并且以确定系数 R2、误差平方和以及均方根误差评价拟合模型的精确度。研究表明：计算结果与文献相吻合。该法运行可靠，无需编程、易于掌握。与传统计算方法相比，操作更为便捷，强有力的图形界面也使计算变得更加简单而直观。% The residence time distribution (RTD) of a chemical reactor is a probability distribution function that describes the amount of time a fluid element could spend inside the reactor. Chemical engineers use the RTD to characterize the mixing and flow within reactors and to compare the behavior of real reactors to their ideal models. This is useful, not only for troubleshooting existing reactors, but in estimating the yield of a given reaction and designing future reactors. The determination of the RTD for a reactor is essential to the reactor flow model. This paper presents a new method to determine the RTD characteristics using MATLAB’s Curve Fitting Toolbox. The acquired data was imported and smoothed via the graphical user interface (GUI). Smoothing spline was used to produce smooth curves to fit to the data, and the RTD characteristics were calculated by numerical integrals. The root-mean-square error (RMSE), error sum of squares (SSE), and determination coefficient (R2) statistics were used to evaluate the model’s accuracy. The study showed that the calculated results are accurate and reliable because they are consistent with those in the literatures. Compared with the traditional calculations, this method provides visualized results, and the GUI simplifies the calculation and makes it intuitive. It can be
Mathematical Modeling of Allelopathy. III. A Model for Curve-Fitting Allelochemical Dose Responses
Liu, De Li; An, Min; Johnson, Ian R.; Lovett, John V.
2003-01-01
Bioassay techniques are often used to study the effects of allelochemicals on plant processes, and it is generally observed that the processes are stimulated at low allelochemical concentrations and inhibited as the concentrations increase. A simple empirical model is presented to analyze this type of response. The stimulation-inhibition properties of allelochemical-dose responses can be described by the parameters in the model. The indices, p% reductions, are calculated to assess the allelochemical effects. The model is compared with experimental data for the response of lettuce seedling growth to Centaurepensin, the olfactory response of weevil larvae to α-terpineol, and the responses of annual ryegrass (Lolium multiflorum Lam.), creeping red fescue (Festuca rubra L., cv. Ensylva), Kentucky bluegrass (Poa pratensis L., cv. Kenblue), perennial ryegrass (L. perenne L., cv. Manhattan), and Rebel tall fescue (F. arundinacea Schreb) seedling growth to leachates of Rebel and Kentucky 31 tall fescue. The results show that the model gives a good description to observations and can be used to fit a wide range of dose responses. Assessments of the effects of leachates of Rebel and Kentucky 31 tall fescue clearly differentiate the properties of the allelopathic sources and the relative sensitivities of indicators such as the length of root and leaf. PMID:19330111
Mathematical Modeling of Allelopathy. III. A Model for Curve-Fitting Allelochemical Dose Responses.
Liu, De Li; An, Min; Johnson, Ian R; Lovett, John V
2003-01-01
Bioassay techniques are often used to study the effects of allelochemicals on plant processes, and it is generally observed that the processes are stimulated at low allelochemical concentrations and inhibited as the concentrations increase. A simple empirical model is presented to analyze this type of response. The stimulation-inhibition properties of allelochemical-dose responses can be described by the parameters in the model. The indices, p% reductions, are calculated to assess the allelochemical effects. The model is compared with experimental data for the response of lettuce seedling growth to Centaurepensin, the olfactory response of weevil larvae to alpha-terpineol, and the responses of annual ryegrass (Lolium multiflorum Lam.), creeping red fescue (Festuca rubra L., cv. Ensylva), Kentucky bluegrass (Poa pratensis L., cv. Kenblue), perennial ryegrass (L. perenne L., cv. Manhattan), and Rebel tall fescue (F. arundinacea Schreb) seedling growth to leachates of Rebel and Kentucky 31 tall fescue. The results show that the model gives a good description to observations and can be used to fit a wide range of dose responses. Assessments of the effects of leachates of Rebel and Kentucky 31 tall fescue clearly differentiate the properties of the allelopathic sources and the relative sensitivities of indicators such as the length of root and leaf.
Nonlinear time series analysis of the light curves from the black hole system GRS1915+105
Institute of Scientific and Technical Information of China (English)
K.P Harikrishnan; Ranjeev Misra; G.Ambika
2011-01-01
GRS 1915+105 is a prominent black hole system exhibiting variability over a wide range of time scales and its observed light curves have been classified into 12 temporal states. Here we undertake a complete analysis of these light curves from all the states using various quantifiers from nonlinear time series analysis, such as the correlation dimension (D2), the correlation entropy (K2), singular value decomposition (SVD) and the multifractal spectrum (f(α) spectrum). An important aspect of our analysis is that, for estimating these quantifiers, we use algorithmic schemes which we have recently proposed and successfully tested on synthetic as well as practical time series from various fields. Though the schemes are based on the conventional delay embedding technique, they are automated so that the above quantitative measures can be computed using conditions prescribed by the algorithm and without any intermediate subjective analysis. We show that nearly half of the 12 temporal states exhibit deviation from randomness and their complex temporal behavior could be approximated by a few (three or four) coupled ordinary nonlinear differential equations. These results could be important for a better understanding of the processes that generate the light curves and hence for modeling the temporal behavior of such complex systems.To our knowledge, this is the first complete analysis of an astrophysical object (let alone a black hole system) using various techniques from nonlinear dynamics.
Directory of Open Access Journals (Sweden)
M. E. Artemenko
2011-03-01
Full Text Available The topological and algebraic conditions for formation of ARC-prototype state equation were obtained to diagnose the possibility of application the compact modified method of curve fitting for parametric synthesis of SC-filter directly on its circuit or element’s connection matrix. The formal mathematical apparatus of forming the ARC-prototype’s compact equation of electric equilibrium on the element’s connection matrix was developed, which allows to reduce the dimension of the synthesized filter to the number of prototype’s capacitors. The relations to account nonideal parameters of operational amplifiers for the prototype’s compact equation of electric equilibrium were obtained, which improve the accuracy of parametric synthesis of switched-capacitor networks.
Marconi, Marcella; Ripepi, Vincenzo; Musella, Ilaria; Brocato, Enzo
2012-01-01
We present a theoretical investigation of multifilter (U,B,V, I and K) light and radial velocity curves of five Classical Cepheids in NGC 1866, a young massive cluster of the Large Magellanic Cloud. The best fit models accounting for the luminosity and radial velocity variations of the five selected variables, four pulsating in the fundamental mode and one in the first overtone, provide direct estimates of their intrinsic stellar parameters and individual distances. The resulting stellar properties indicate a slightly brighter Mass Luminosity relation than the canonical one, possibly due to mild overshooting and/or mass loss. As for the inferred distances, the individual values are consistent within the uncertainties. Moreover, their weighted mean value corresponds to a distance modulus of 18.56 + - 0.03 (stat) + - 0.1 (syst) mag, in agreement with several independent results in the literature.
Bradley, B.; Mustard, J.; Jacob, R.; Hermance, J.
2005-12-01
Annual, inter-annual, and long-term trends in Land Surface Phenology (LSP) using NDVI time series from AVHRR and MODIS can be used to distinguish between natural ecosystem dynamics and land cover change. However, the full potential of long-term NDVI time series is often hampered by poor quality data caused by instrumentation problems, atmospheric conditions (e.g. clouds or haze), ground conditions (e.g. snow), and inter-annual variability of land cover. These effects make LSP difficult to identify, and may mask subtle shifts in inter-annual ecosystem response resulting from land use or other anthropogenic forcing. In order to maximize LSP detection, we use a curve fitting methodology useful for long-term time series across a range of phenologies. This approach is minimally affected by sensor error, clouds, and snow, and requires neither spatial nor temporal averaging to reduce noise. This methodology employs a spline-based curve, which is fit iteratively so that positive residuals are upweighted to capture the upper envelope of NDVI values. Here, we apply the curve fitting methodology to weekly AVHRR NDVI data (1990-2000) and biweekly MODIS NDVI data (2000-2005) at 1 km pixel resolution for the Great Basin desert of the western U.S. The spatial and temporal patterns of known ecosystems may then be assessed in order to identify anomalous trends in regional LSP. We compare both spatial and temporal variability of four known ecosystem types surveyed in 2004: sagebrush steppe, cheatgrass grassland, pinyon-juniper woodland, and montane shrubland. Average onset of greenness (using a timing of half max technique) occurred on Apr 14 (+/- 6 days; sagebrush), Apr 9 (+/- 8 days; cheatgrass), Apr 17 (+/- 8 days; pinyon-juniper) and May 24 (+/- 5 days; montane). The small standard deviation observed in similar ecosystems distributed throughout the Great Basin indicates that the phenologies are spatially robust in any individual year. However, there is considerable temporal
Tiffany, S. H.; Adams, W. M., Jr.
1984-01-01
A technique which employs both linear and nonlinear methods in a multilevel optimization structure to best approximate generalized unsteady aerodynamic forces for arbitrary motion is described. Optimum selection of free parameters is made in a rational function approximation of the aerodynamic forces in the Laplace domain such that a best fit is obtained, in a least squares sense, to tabular data for purely oscillatory motion. The multilevel structure and the corresponding formulation of the objective models are presented which separate the reduction of the fit error into linear and nonlinear problems, thus enabling the use of linear methods where practical. Certain equality and inequality constraints that may be imposed are identified; a brief description of the nongradient, nonlinear optimizer which is used is given; and results which illustrate application of the method are presented.
Directory of Open Access Journals (Sweden)
Rongda Chen
Full Text Available Recovery rate is essential to the estimation of the portfolio's loss and economic capital. Neglecting the randomness of the distribution of recovery rate may underestimate the risk. The study introduces two kinds of models of distribution, Beta distribution estimation and kernel density distribution estimation, to simulate the distribution of recovery rates of corporate loans and bonds. As is known, models based on Beta distribution are common in daily usage, such as CreditMetrics by J.P. Morgan, Portfolio Manager by KMV and Losscalc by Moody's. However, it has a fatal defect that it can't fit the bimodal or multimodal distributions such as recovery rates of corporate loans and bonds as Moody's new data show. In order to overcome this flaw, the kernel density estimation is introduced and we compare the simulation results by histogram, Beta distribution estimation and kernel density estimation to reach the conclusion that the Gaussian kernel density distribution really better imitates the distribution of the bimodal or multimodal data samples of corporate loans and bonds. Finally, a Chi-square test of the Gaussian kernel density estimation proves that it can fit the curve of recovery rates of loans and bonds. So using the kernel density distribution to precisely delineate the bimodal recovery rates of bonds is optimal in credit risk management.
Moving curved surface fitting based on Kriging statistics%基于Kriging统计的移动曲面拟合
Institute of Scientific and Technical Information of China (English)
管莉莉; 李明峰; 卢扣; 陈春晖
2011-01-01
通过方位取点法选取采样点,移动拟合出二次曲面来逼近实际地形.对采样点处的逼近误差进行Kriging统计,获得待定点处高程逼近误差的最优估值.进行了基于Kriging统计的移动曲面拟合综合模型的模拟计算,通过单一曲面模型和Kriging统计模型的逼近误差及精度的比较,验证了综合内插模型的优越性.%Sampling points were selected by method of bearing point sampling, moving curved surface fits a quadratic surface to the real terrain. It solves optimal estimation of approximation error in unknown point by Kriging statistics of approximation error in sampling points. Simulation of mobile camber fitting model based on Kriging statistics was carried out. By comparison of approximation error and precision between single surface model and Kriging statistic model, it is verified that the interpolation comprehensive model has its advantage.
Analysis of the nonlinear dynamics of a 2-axle freight wagon in curves
DEFF Research Database (Denmark)
Di Gialleonardo, Egidio; Bruni, Stefano; True, Hans
2014-01-01
and bifurcations are identified for some particular values of the curve radius. For the single car case, it is shown that depending on the curve radius and the vehicle speed the carbody may experience severe periodic oscillations at speeds lying in the operating range of the vehicle. For the car-assembly case...
曲线拟合在血细胞分析中的应用%The Application of Curve Fitting among Analysis of Blood Cells
Institute of Scientific and Technical Information of China (English)
吴义满
2011-01-01
Objective The measurement error is fairly great in blood cell analyzer at present. To reduce the error, the curve fitting model based on Matlab is supposed to be applied. Methods The errors of the platelet count in measurement and Coulter theory were corrected with the method of curve fitting in this paper. Results The two examples with curve fitting method were completed and their results indicated that curve fitting based on Matlab was feasible and valid for correcting the errors from measurements. Conclusions Curve fitting based on Matlab is useful to correct the measurement error of blood cells.%目的 常见的血细胞分析仪测试误差比较大.为减小血细胞的测试误差,可以用Matlab进行曲线拟合的方法修正.方法 本文提出了用曲线拟合来修正血小板计数的测试误差和库尔特原理误差.结果 通过两个实例证明了曲线拟合修正血细胞的测试误差是可行和有效的.结论 利用Matlab曲线拟合修正血细胞的测试误差有一定实际意义.
Nonlinear dynamics for charges particle beams with a curved axis in the matrix - recursive model
Energy Technology Data Exchange (ETDEWEB)
Dymnikov, A.D. [University of St Petersburg, (Russian Federation). Institute of Computational Mathematics and Control Process
1993-12-31
In this paper a new matrix and recursive approach has been outlined for treating nonlinear optics of charged particle beams. This approach is a new analytical and computational tool for designers of optimal beam control systems. 9 refs.
Martin, Y. L.
The performance of quantitative analysis of 1D NMR spectra depends greatly on the choice of the NMR signal model. Complex least-squares analysis is well suited for optimizing the quantitative determination of spectra containing a limited number of signals (20). From a general point of view it is concluded, on the basis of mathematical considerations and numerical simulations, that, in the absence of truncation of the free-induction decay, complex least-squares curve fitting either in the time or in the frequency domain and linear-prediction methods are in fact nearly equivalent and give identical results. However, in the situation considered, complex least-squares analysis in the frequency domain is more flexible since it enables the quality of convergence to be appraised at every resonance position. An efficient data-processing strategy has been developed which makes use of an approximate conjugate-gradient algorithm. All spectral parameters (frequency, damping factors, amplitudes, phases, initial delay associated with intensity, and phase parameters of a baseline correction) are simultaneously managed in an integrated approach which is fully automatable. The behavior of the error as a function of the signal-to-noise ratio is theoretically estimated, and the influence of apodization is discussed. The least-squares curve fitting is theoretically proved to be the most accurate approach for quantitative analysis of 1D NMR data acquired with reasonable signal-to-noise ratio. The method enables complex spectral residuals to be sorted out. These residuals, which can be cumulated thanks to the possibility of correcting for frequency shifts and phase errors, extract systematic components, such as isotopic satellite lines, and characterize the shape and the intensity of the spectral distortion with respect to the Lorentzian model. This distortion is shown to be nearly independent of the chemical species, of the nature of the molecular site, and of the type of nucleus, but
Wei, Shao-Wen
2014-01-01
In this paper, we first review the equal area laws and Clapeyron equations in the extended phase space of the charged AdS black holes. With different fixed parameters, the Maxwell's equal area law not only hold in $P-V$ (pressure-thermodynamic volume) oscillatory line, but also in $Q-\\Phi$ (charge-electric potential) and $T-S$ (temperature-entropy) oscillatory lines. The classical Clapeyron equation also obtains its generalizations that two extra equations are found. Moreover, we present the fitting formula of the coexistence curve that the small and large charged black holes coexist. The result shows that the fitting formula is charge independent in the reduced parameter space for any dimension of spacetime. Using such analytic expression of the coexistence curve, we find that the Clapeyron equations are highly consistent with the calculated values. The fitting formula is useful for further study on the thermodynamic property of the system varying along the coexistence curve.
Energy Technology Data Exchange (ETDEWEB)
Abbas, Z.; Naveed, M., E-mail: rana.m.naveed@gmail.com [Department of Mathematics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Sajid, M. [Theoretical Physics Division, PINSTECH, P.O. Nilore, Islamabad 44000 (Pakistan)
2015-10-15
In this paper, effects of Hall currents and nonlinear radiative heat transfer in a viscous fluid passing through a semi-porous curved channel coiled in a circle of radius R are analyzed. A curvilinear coordinate system is used to develop the mathematical model of the considered problem in the form partial differential equations. Similarity solutions of the governing boundary value problems are obtained numerically using shooting method. The results are also validated with the well-known finite difference technique known as the Keller-Box method. The analysis of the involved pertinent parameters on the velocity and temperature distributions is presented through graphs and tables.
Włosińska, M.; Niedzielski, T.; Priede, I. G.; Migoń, P.
2012-04-01
The poster reports ongoing investigations into hypsometric curve modelling and its implications for sea level change. Numerous large-scale geodynamic phenomena, including global tectonics and the related sea level changes, are well described by a hypsometric curve that quantifies how the area of sea floor varies along with depth. Although the notion of hypsometric curve is rather simple, it is difficult to provide a reasonable theoretical model that fits an empirical curve. An analytical equation for a hypsometric curve is well known, but its goodness-of-fit to an empirical one is far from perfect. Such a limited accuracy may result from either not entirely adequate theoretical assumptions and concepts of a theoretical hypsometric curve or rather poorly modelled global bathymetry. Recent progress in obtaining accurate data on sea floor topography is due to subsea surveying and remote sensing. There are bathymetric datasets, including Global Bathymetric Charts of the Oceans (GEBCO), that provide a global framework for hypsometric curve computation. The recent GEBCO bathymetry - a gridded dataset that consists a sea floor topography raster revealing a global coverage with a spatial resolution of 30 arc-seconds - can be analysed to verify a depth-area relationship and to re-evaluate classical models for sea level change in geological time. Processing of the geospatial data is feasible on the basis of modern powerful tools provided by Geographic Information System (GIS) and automated with Python, the programming language that allows the user to utilise the GIS geoprocessor.
Institute of Scientific and Technical Information of China (English)
叶伟庆; 杜炳旺; 刘宜林; 陈运冬; 陈建; 李东华
2014-01-01
Xinyi HuaiXiang Chicken is a famous chicken breed that listed in the National Animal Genetic Resources Protection List,the study of early growth rules of Xinyi HuaiXiang chicken provide a evidence for its genetic resources conservation and trains breeding.The growth curve of A,B strains of HuaiXiang hen from 0 to 9 weeks old was analyzed and fitted with three kinds of nonlinear models (Gompertz, Logistic, von Bertalanffy).The growth curves were appropriately fitted with three models. The Bertalanffy model had the best effect on fitting with the growth curves of A strain hen (R2=0.996), its growth inflexion was 10.165 weeks and 1047.7g.;The Gompertz model had the best effect on fitting with the growth curves of B strain hen(R2=0.997), its growth inflexion was 8.008 weeks and 748.3g.It is feasible to analyze and fit the growth curve of the HuaiXiang chicken using the three models.%信宜怀乡鸡作为列入国家畜禽遗传资源保护名录的著名品种，为了解其肉种鸡的早期生长发育规律，为其遗传资源保护和品系选育提供参考依据。使用Logistic、Gompertz和Bertallanffy 3种非线性生长模型对怀乡鸡A、B两个品系母鸡0~9周龄早期体重生长数据进行曲线拟合和分析。3种模型均能很好地模拟怀乡鸡生长曲线，Bertalanffy模型的拟合A品系母鸡生长效果最佳（R2=0.996），其拐点为（10.165，1047.7）；Gompertz模型的拟合B品系母鸡生长效果最佳（R2=0.997），其拐点为（8.008，748.3）。3种模型对信宜怀乡鸡生长曲线的拟合和分析是可行的，可及时掌握怀乡鸡的生长发育规律。
Schaling, E.
1998-01-01
We extend the Svensson (1997a) inflation forecast targeting framework with a convex Phillips curve. We derive an asymmetric target rule, that implies a higher level of nominal interest rates than the Svensson (1997a) forward looking version of the reaction function popularised by Taylor (1993).
Schaling, E.
1998-01-01
We extend the Svensson (1997a) inflation forecast targeting framework with a convex Phillips curve. We derive an asymmetric target rule, that implies a higher level of nominal interest rates than the Svensson (1997a) forward looking version of the reaction function popularised by Taylor (1993). Exte
Alexander, John W., Jr.; Rosenberg, Nancy S.
This document consists of two modules. The first of these views applications of algebra and elementary calculus to curve fitting. The user is provided with information on how to: 1) construct scatter diagrams; 2) choose an appropriate function to fit specific data; 3) understand the underlying theory of least squares; 4) use a computer program to…
Modeling of non-linear CHP efficiency curves in distributed energy systems
DEFF Research Database (Denmark)
Milan, Christian; Stadler, Michael; Cardoso, Gonçalo
2015-01-01
Distributed energy resources gain an increased importance in commercial and industrial building design. Combined heat and power (CHP) units are considered as one of the key technologies for cost and emission reduction in buildings. In order to make optimal decisions on investment and operation...... for these technologies, detailed system models are needed. These models are often formulated as linear programming problems to keep computational costs and complexity in a reasonable range. However, CHP systems involve variations of the efficiency for large nameplate capacity ranges and in case of part load operation......, which can be even of non-linear nature. Since considering these characteristics would turn the models into non-linear problems, in most cases only constant efficiencies are assumed. This paper proposes possible solutions to address this issue. For a mixed integer linear programming problem two...
Bi-Hamiltonian Structure of a Third-Order Nonlinear Evolution Equation on Plane Curve Motions
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In the present paper, we identify the integrability of the third-order nonlinear evolution equation ut = (1/2)((uxx + u)-2)x in a Hamiltonian viewpoint. We prove that the recursion operator obtained by S. Yu. Sakovich is hereditary, and then deduce a bi-Hamiltonian structure of the equation by using some decomposition of the hereditary operator. A hierarchy associated to the equation is also shown.
Neitzel, Anne-Christin; Stamer, Eckhard; Junge, Wolfgang; Thaller, Georg
2015-05-01
Laboratory somatic cell count (LSCC) records are usually recorded monthly and provide an important information source for breeding and herd management. Daily milk viscosity detection in composite milking (expressed as drain time) with an automated on-line California Mastitis Test (CMT) could serve immediately as an early predictor of udder diseases and might be used as a selection criterion to improve udder health. The aim of the present study was to clarify the relationship between the well-established LSCS and the new trait,'drain time', and to estimate their correlations to important production traits. Data were recorded on the dairy research farm Karkendamm in Germany. Viscosity sensors were installed on every fourth milking stall in the rotary parlour to measure daily drain time records. Weekly LSCC and milk composition data were available. Two data sets were created containing records of 187,692 milkings from 320 cows (D1) and 25,887 drain time records from 311 cows (D2). Different fixed effect models, describing the log-transformed drain time (logDT), were fitted to achieve applicable models for further analysis. Lactation curves were modelled with standard parametric functions (Ali and Schaeffer, Legendre polynomials of second and third degree) of days in milk (DIM). Random regression models were further applied to estimate the correlations between cow effects between logDT and LSCS with further important production traits. LogDT and LSCS were strongest correlated in mid-lactation (r = 0.78). Correlations between logDT and production traits were low to medium. Highest correlations were reached in late lactation between logDT and milk yield (r = -0.31), between logDT and protein content (r = 0.30) and in early as well as in late lactation between logDT and lactose content (r = -0.28). The results of the present study show that the drain time could be used as a new trait for daily mastitis control.
Guo, Lianping; Tian, Shulin; Jiang, Jun
2015-03-01
This paper proposes an algorithm to estimate the channel mismatches in time-interleaved analog-to-digital converter (TIADC) based on fractional delay (FD) and sine curve fitting. Choose one channel as the reference channel and apply FD to the output samples of reference channel to obtain the ideal samples of non-reference channels with no mismatches. Based on least square method, the sine curves are adopted to fit the ideal and the actual samples of non-reference channels, and then the mismatch parameters can be estimated by comparing the ideal sine curves and the actual ones. The principle of this algorithm is simple and easily understood. Moreover, its implementation needs no extra circuits, lowering the hardware cost. Simulation results show that the estimation accuracy of this algorithm can be controlled within 2%. Finally, the practicability of this algorithm is verified by the measurement results of channel mismatch errors of a two-channel TIADC prototype.
Kumar, P. Ramesh; Gunaseelan, R.; Raj, A. Antony; Selvakumar, S.; Sagayaraj, P.
2012-06-01
Nonlinear optical amino-acid single crystal of L-phenylalanine hydrochloride (LPHCl) was successfully grown by unidirectional Sankaranarayanan-Ramasamy (SR) method under ambient conditions for the first time. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. The crystalline perfection was evaluated using high-resolution X-ray diffractometry. It is evident from the optical absorption study that crystal has excellent transmission in the entire visible region with its lower cut off wavelength around 290 nm.
Fitting Centrifugal Pump Performance Curve Based on Visual Basic%基于Visual Basic编程对离心泵性能曲线的拟合
Institute of Scientific and Technical Information of China (English)
刘红明; 孙铁; 刘嵩; 王亮; 魏佳广
2014-01-01
Centrifugal pump performance curve is the basis of measuring the performance, type selection calculation and optimal operation of the centrifugal pump. After the test,in order to get more accurate data based on the sampling point, curve of experimental data needs to be fitted. In this paper, taking fitting flow and head curve of centrifugal pump as an example, the method to fit the curve by programming based visual basic with the least square method was introduced. The practical application has proved that the method has many advantages, and can effectively solve data processing problems in centrifugal pump type selection and curve fitting in petrochemical industry.%在分析拟合离心泵性能曲线必要性的基础上，以拟合离心泵流量和扬程性能曲线为例，介绍了利用最小二乘法使用visual Basic语言进行直接编程拟合曲线的方法；经实际使用本程序具有简单、易用、求解效率高、适用范围广等特点，有效解决了石化行业中离心泵选型、试验中曲线拟合的数据处理问题，可以在离心泵及容积泵性能曲线拟合中推广应用。
Institute of Scientific and Technical Information of China (English)
Mehran Vahdani Moghaddam; Zeynab Chenari; Hamid Latifi; Vladimir Vladimirovich Shuvalov; Konestantin Valentinovich Rudenko
2008-01-01
@@ We deal with computer simulation of a transient process in a self-pumped phase conjugate plane-curve loop mirror based on BaTiO3. In optimal circumstances the nonlinear reflectivity and fidelity of such a mirror respectively achieve 0.80-0.90 and 0.95-0.98. The generation of conjugate wave-front occurs due to scattering from the dynamic hologram which is produced in the region of self-intersection of forward and backward beams. In such a model the scenario of passing to unstable generation regimes is similar to the self-pumped phase conjugate plane-plane loop mirror and substantially differs from a single-crystal double phase conjugate mirror.
Strategies for fitting nonlinear ecological models in R, AD Model Builder, and BUGS
DEFF Research Database (Denmark)
Bolker, B.M.; Gardner, B.; Maunder, M.
2013-01-01
) to specific suggestions about how to change the mathematical description of models to make them more amenable to parameter estimation. A companion web site (https://groups.nceas.ucsb.edu/nonlinear-modeling/projects) presents detailed examples of application of the three tools to a variety of typical...
Dijkstra, T.K.; Henseler, J.
2011-01-01
The recent advent of nonlinear structural equation models with indices poses a new challenge to the measurement of scientific constructs. We discuss, exemplify and add to a family of statistical methods aimed at creating linear indices, and compare their suitability in a complex path model with line
Energy Technology Data Exchange (ETDEWEB)
Birchler, W.D.; Schilling, S.A.
2001-02-01
The purpose of this report is to demonstrate that modern computer-aided design (CAD), computer-aided manufacturing (CAM), and computer-aided engineering (CAE) systems can be used in the Department of Energy (DOE) Nuclear Weapons Complex (NWC) to design new and remodel old products, fabricate old and new parts, and reproduce legacy data within the inspection uncertainty limits. In this study, two two-dimensional splines are compared with several modern CAD curve-fitting modeling algorithms. The first curve-fitting algorithm is called the Wilson-Fowler Spline (WFS), and the second is called a parametric cubic spline (PCS). Modern CAD systems usually utilize either parametric cubic and/or B-splines.
Energy Technology Data Exchange (ETDEWEB)
Szabó, Róbert; Ivezić, Željko; Kiss, László L.; Kolláth, Zoltán [Konkoly Observatory, MTA CSFK, Konkoly Thege Miklós út 15-17, H-1121 Budapest (Hungary); Jones, Lynne; Becker, Andrew C.; Davenport, James R. A. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Sesar, Branimir [Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125 (United States); Cutri, Roc M., E-mail: rszabo@konkoly.hu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
2014-01-01
We present and discuss an extensive data set for the non-Blazhko ab-type RR Lyrae star SDSS J015450+001501, including optical Sloan Digital Sky Survey ugriz light curves and spectroscopic data, LINEAR and Catalina Sky Survey unfiltered optical light curves, and infrared Two Micron All Sky Survey (2MASS) JHK{sub s} and Wide-field Infrared Survey Explorer W1 and W2 light curves. Most notable is that light curves obtained by 2MASS include close to 9000 photometric measures collected over 3.3 yr and provide an exceedingly precise view of near-infrared variability. These data demonstrate that static atmosphere models are insufficient to explain multiband photometric light-curve behavior and present strong constraints for nonlinear pulsation models for RR Lyrae stars. It is a challenge to modelers to produce theoretical light curves that can explain data presented here, which we make publicly available.
O'Neil, Sean F; Mac, Amy; Rhodes, Gillian; Webster, Michael A
2015-12-01
Recently, we proposed that the aftereffects of adapting to facial age are consistent with a renormalization of the perceived age (e.g., so that after adapting to a younger or older age, all ages appear slightly older or younger, respectively). This conclusion has been challenged by arguing that the aftereffects can also be accounted for by an alternative model based on repulsion (in which facial ages above or below the adapting age are biased away from the adaptor). However, we show here that this challenge was based on allowing the fitted functions to take on values which are implausible and incompatible across the different adapting conditions. When the fits are constrained or interpreted in terms of standard assumptions about normalization and repulsion, then the two analyses both agree in pointing to a pattern of renormalization in age aftereffects.
酉州乌羊生长曲线拟合分析研究%Study on growth curve fitting of YouZhou Black Goat
Institute of Scientific and Technical Information of China (English)
方亚; 黄勇富; 王高富
2011-01-01
对酉州乌羊体重随月龄增长应用Logistic、Gompertz、Richards模型进行生长曲线拟合分析,建立公、母羊的拟合曲线方程及求出拐点体重、拐点月龄。结果表明：三种模型均能很好地拟合公、母羊生长规律,Logistic、Gompertz、Richards模型拟合公羊的拟合度（R2）分别为0.987、0.995、0.987,母羊拟合度（R2）0.968、0.9810.968,三种模型相互比较,Gompertz模型拟合效果最好。%Youzhou black goats weight increase with age application Logistic, Gompertz, Richardss model for growth curve fitting analysis, male goat and famale goat＇s equation and find the Inflexion point of body weight, Inflexion age. maximal growth rate.The results showed that：three models can fit male goat and famale goat growth pattern, Logistic, Gompertz, Richards three model fitting male goat goodness of fit （R2） were 0.987,0.995,0.987,famale goat goodness of fit （R2） 0.968,0.981 0.968, three models compare with each other, Gompertz model fit the best.
Fitness Effects of Network Non-Linearity Induced by Gene Expression Noise
Ray, Christian; Cooper, Tim; Balazsi, Gabor
2012-02-01
In the non-equilibrium dynamics of growing microbial cells, metabolic enzymes can create non-linearities in metabolite concentration because of non-linear degradation (utilization): an enzyme can saturate in the process of metabolite utilization. Increasing metabolite production past the saturation point then results in an ultrasensitive metabolite response. If the production rate of a metabolite depends on a second enzyme or other protein-mediated process, uncorrelated gene expression noise can thus cause transient metabolite concentration bursts. Such bursts are physiologically unnecessary and may represent a source of selection against the ultrasensitive switch, especially if the fluctuating metabolic intermediate is toxic. Selection may therefore favor correlated gene expression fluctuations for enzymes in the same pathway, such as by same-operon membership in bacteria. Using a modified experimental lac operon system, we are undertaking a combined theoretical-experimental approach to demonstrate that (i) the lac operon has an implicit ultrasensitive switch that we predict is avoided by gene expression correlations induced by same-operon membership; (ii) bacterial growth rates are sensitive to crossing the ultrasensitive threshold. Our results suggest that correlations in intrinsic gene expression noise are exploited by evolution to ameliorate the detrimental effects of nonlinearities in metabolite concentrations.
Calibration of Vector Magnetogram with the Nonlinear Least-squares Fitting Technique
Institute of Scientific and Technical Information of China (English)
Jiang-Tao Su; Hong-Qi Zhang
2004-01-01
To acquire Stokes profiles from observations of a simple sunspot with the Video Vector Magnetograph at Huairou Solar Observing Station(HSOS),we scanned the FeIλ5324.19 A line over the wavelength interval from 150mA redward of the line center to 150mA blueward,in steps of 10mA.With the technique of analytic inversion of Stokes profiles via nonlinear least-squares,we present the calibration coefficients for the HSOS vector magnetic magnetogram.We obtained the theoretical calibration error with linear expressions derived from the Unno-Becker equation under weak-field approximation.
Bhattacharya, Kolahal; Banerjee, Sudeshna; Mondal, Naba K.
2016-07-01
In the context of track fitting problems by a Kalman filter, the appropriate functional forms of the elements of the random process noise matrix are derived for tracking through thick layers of dense materials and magnetic field. This work complements the form of the process noise matrix obtained by Mankel [1].
Energy Technology Data Exchange (ETDEWEB)
Saunders, C.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Kim, A. G. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J. [Laboratoire de Physique Nucléaire et des Hautes Énergies, Université Pierre et Marie Curie Paris 6, Université Paris Diderot Paris 7, CNRS-IN2P3, 4 Place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Chotard, N.; Copin, Y.; Gangler, E. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, Institut de Physique Nucléaire de Lyon, 69622 Villeurbanne (France); Feindt, U.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universität Bonn, Nußallee 12, D-53115 Bonn (Germany); and others
2015-02-10
We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a given supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion greater than ∼0.05 mag for measurements of photometry using the Sloan-like filters and a bias that corresponds to a 0.03 shift in w when applied to an outside data set. To test the result of a shift in supernova population or environment at higher redshifts, we repeat our calculations with the addition of a reweighting of the supernovae as a function of redshift and find that this strongly affects the results and would have repercussions for cosmology. We discuss possible methods to reduce the contribution of the K-correction bias and uncertainty.
Rong, Youmin; Zhang, Guojun; Huang, Yu
2016-10-01
Inherent strain analysis has been successfully applied to predict welding deformations of large-scale structural components, while thermal-elastic-plastic finite element method is rarely used for its disadvantages of long calculation period and large storage space. In this paper, a hybrid model considering nonlinear yield stress curves and multi-constraint equations to thermal-elastic-plastic analysis is further proposed to predict welding distortions and residual stresses of large-scale structures. For welding T-joint structural steel S355JR by metal active gas welding, the published experiment results of temperature and displacement fields are applied to illustrate the credibility of the proposed integration model. By comparing numerical results of four different cases with the experiment results, it is verified that prediction precision of welding deformations and residual stresses is apparently improved considering the power-law hardening model, and computational time is also obviously shortened about 30.14% using multi-constraint equations. On the whole, the proposed hybrid method can be further used to precisely and efficiently predict welding deformations and residual stresses of large-scale structures.
Fitting method of pseudo-polynomial for solving nonlinear parametric adjustment
Institute of Scientific and Technical Information of China (English)
陶华学; 宫秀军; 郭金运
2001-01-01
The optimal condition and its geometrical characters of the least-square adjustment were proposed. Then the relation between the transformed surface and least-squares was discussed. Based on the above, a non-iterative method, called the fitting method of pseudo-polynomial, was derived in detail. The final least-squares solution can be determined with sufficient accuracy in a single step and is not attained by moving the initial point in the view of iteration. The accuracy of the solution relys wholly on the frequency of Taylor's series. The example verifies the correctness and validness of the method.
Directory of Open Access Journals (Sweden)
G. Milani
2016-01-01
Full Text Available A GUI software (GURU for experimental data fitting of rheometer curves in Natural Rubber (NR vulcanized with sulphur at different curing temperatures is presented. Experimental data are automatically loaded in GURU from an Excel spreadsheet coming from the output of the experimental machine (moving die rheometer. To fit the experimental data, the general reaction scheme proposed by Han and co-workers for NR vulcanized with sulphur is considered. From the simplified kinetic scheme adopted, a closed form solution can be found for the crosslink density, with the only limitation that the induction period is excluded from computations. Three kinetic constants must be determined in such a way to minimize the absolute error between normalized experimental data and numerical prediction. Usually, this result is achieved by means of standard least-squares data fitting. On the contrary, GURU works interactively by means of a Graphical User Interface (GUI to minimize the error and allows an interactive calibration of the kinetic constants by means of sliders. A simple mouse click on the sliders allows the assignment of a value for each kinetic constant and a visual comparison between numerical and experimental curves. Users will thus find optimal values of the constants by means of a classic trial and error strategy. An experimental case of technical relevance is shown as benchmark.
An improved nonlinear model of HEMTs with independent transconductance tail-off fitting
Institute of Scientific and Technical Information of China (English)
Liu Linsheng
2011-01-01
We present an improved large-signal device model of GaAs/GaN HEMTs, amenable for use in commercial nonlinear simulators. The proposed model includes a new exponential function to independently control the transconductance compression/tail-offbehaviors. The main advantage of this model is to provide a simple and coherent description of the bias-dependent drain current (I-V) that is valid in all regions of operation. All aspects of the model are validated for 0.25-μm gate-length GaAs and GaN HEMT processes. The simulation results of DC/pulsed I-V, RF large-signal power and intermodulation distortion products show excellent agreement with the measured data.
Calzado, Carmen J
2013-01-21
This paper reports a theoretical analysis of the electronic structure and magnetic properties of a tetranuclear Cu(II) complex, [Cu(4) (HL)(4)], which has a 4+2 cubane-like structure (H(3) L=N,N'-(2-hydroxypropane-1,3-diyl)bis(acetylacetoneimine)). These theoretical calculations indicate a quintet (S=2) ground state; the energy-level distribution of the magnetic states confirm Heisenberg behaviour and correspond to an S(4) spin-spin interaction model. The dominant interaction is the ferromagnetic coupling between the pseudo-dimeric units (J(1) =22.2 cm(-1)), whilst a weak and ferromagnetic interaction is found within the pseudo-dimeric units (J(2) =1.4 cm(-1)). The amplitude and sign of these interactions are consistent with the structure and arrangement of the magnetic Cu 3d orbitals; they accurately simulate the thermal dependence of magnetic susceptibility, but do not agree with the reported J values (J(1) =38.4 cm(-1), J(2) =-18.0 cm(-1)) that result from the experimental fitting. This result is not an isolated case; many other polynuclear systems, in particular 4+2 Cu(II) cubanes, have been reported in which the fitted magnetic terms are not consistent with the geometrical features of the system. In this context, theoretical evaluation can be considered as a valuable tool in the interpretation of the macroscopic behaviour, thus providing clues for a rational and directed design of new materials with specific properties.
Institute of Scientific and Technical Information of China (English)
陈家权; 陈国军; 陈非凡; 张云泉; 温洁明
2011-01-01
Box-Cox variable transform fitting method based on variable transformation method was presented, in order to solve fitting problems of three-parameter P-S-N curves under the logarithm fatigue life of different stress levels, which does not meet the normal linear regression Gauss-Markov assumptions. The effectiveness and reliability of this method has been verified by selected test data of the LC4, 40CrNiMo and LY12CS. Analysis of experimental data showed that fitting results of estimating three parameters of P-S-N curves by this method is better than the least square method, the relative error of curves fitting in two kinds of reliability could reduce to 1/2 of the least square method, and to 1/4 at most, so that the residual deviation of transformed model reached minimum, improved and stabilized distribution of the residual deviation of this model, also obtained the best linear unbiased estimate of regression coefficient. Finally, a greater ability of non-linear power function model was obtained after being restored transformation to enhance the accuracy and credibility of fitting three-parameter P-S-N curves on original data.%提出一种基于变量变换法的Box-Cox变量变换拟合法,可以解决不同应力水平下对数疲劳寿命不满足正态线性Gauss-Markov假设的三参数P-S-N曲线拟合问题;选取LC4、40CrNiMo和LY12CS材料的试验数据对文中方法的有效性和可靠性进行验证.数据分析表明,文中方法估计的三参数P-S-N曲线比利用最小二乘法的拟合效果更好.在两种可靠度下曲线拟合的相对误差可降低至最小二乘法拟合的1/2,最大可降低至1/4,使变换后的模型残差达到最小.改善并稳定了回归模型的残差分布,得到回归系数估计值的最佳无偏估计,还原变换后得到非线性能力较强的幂函数模型,从而提高原始数据的三参数P-S-N曲线的拟合精度和可信度.
Ho, Kwok M
2017-08-31
Area under a receiver-operating-characteristic (AUROC) curve is widely used in medicine to summarize the ability of a continuous predictive marker to predict a binary outcome. This study illustrated how a U-shaped or inverted U-shaped continuous predictor would affect the shape and magnitude of its AUROC curve in predicting a binary outcome by comparing the ROC curves of the worst first 24-hour arterial pH values of 9549 consecutive critically ill patients in predicting hospital mortality before and after centering the predictor by its mean or median. A simulation dataset with an inverted U-shaped predictor was used to assess how this would affect the shape and magnitude of the AUROC curve. An asymmetrical U-shaped relationship between pH and hospital mortality, resulting in an inverse-sigmoidal ROC curve, was observed. The AUROC substantially increased after centering the predictor by its mean (0.611 vs 0.722, difference = 0.111, 95% confidence interval [CI] 0.087-0.135), and was further improved after centering by its median (0.611 vs 0.745, difference = 0.133, 95%CI 0.110-0.157). A sigmoidal-shaped ROC curve was observed for an inverted U-shaped predictor. In summary, a non-linear predictor can result in a biphasic-shaped ROC curve; and centering the predictor can reduce its bias towards null predictive ability.
Institute of Scientific and Technical Information of China (English)
杜川; 梁秀娟; 张茜; 陈章; 李文娟
2014-01-01
Pumping test is the main method to obtain aquifer hydrogeological parameters and the results directly affect the recognizing and exploita-tion of the hydrogeological conditions of study area. The traditional methods have the problems of being effected easily by subjective judgment and external environmental conditions,taking long time to calculate and lacking data about pumping stage. This paper used the entire curve fitting method and Aquifertest software from the standard curve method and recovery method to calculate parameters individually,and combined with the entire curve fitting method to determine the final value. The results show that using Aquifertest software method to calculate parameters is convenient and accurate;the results have smaller differences using water level recovery method;and the entire curve fitting method has the advantage of unique-ness and reliability in deciding the parameters. Combining different methods can more truly reflect the hydrogeological conditions.%抽水试验是获取含水层水文地质参数的主要方法，求参结果直接影响对调查区水文地质条件的认识和地下水开发利用。传统求参方法存在主观影响大、求参时间长、易受外界影响和抽水阶段数据的不足等问题。通过全程曲线拟合法和 Aquifertest 软件分别从配线法和水位恢复法两个角度进行求参，并结合全程曲线拟合法确定最终取值。结果表明，采用 Aquifertest 软件求参便捷、准确，与水位恢复法求参结果的差异相对较小，全程曲线拟合法求参值具有唯一性和可靠性，多种方法结合求参能更真实反映水文地质情况。
Moving Least-Square Method Applied in NURBS Curve Fitting%移动最小二乘法在NURBS曲线拟合中的应用
Institute of Scientific and Technical Information of China (English)
叶晶; 平雪良; 陶宇; 董宁
2011-01-01
A method for the NURBS curve firing based on moving least-square method(MLS) is presented. It enhanced precision and smoothness of the firing curve based on the traditional least-square method. The principles and characteristics of MLS are described in detail. With the point data of screw rotor as an example, the method is demonstrated by MATLAB and compared with the fitting curve based on the traditional least-square.%在NURBS曲线拟合中采用移动最小二乘(Moving Least-Squares)方法,提高了采用传统最小二乘方法得到的拟合曲线的精度及光滑性.详细介绍了移动最小二乘法(MLS)应用于NURBS曲线拟合的原理及特点;以螺杆转子端面点云数据为实例在MATLAB中实现了移动最小二乘NURBS曲线拟合,并将其与传统最小二乘NURBS拟合结果进行了比较.
Directory of Open Access Journals (Sweden)
2007-09-01
Full Text Available Este texto apresenta uma investigação relativa às características e tendências da acumulação flexível que embalam o desenvolvimento do mercado do fitness. Trata-se de um estudo a partir do caso da Curves Brasil. Para tanto, buscamos confrontar e examinar a implementação de técnicas organizacionais com eficácia evidenciada em escala mundial através do princípio da verificação de um caso particular e real de desenvolvimento. As conclusões apontam para novas técnicas de inovação utilizadas para resolver a difícil equação enfrentada pelo setor no que diz respeito à atração e à retenção de consumidores. PALAVRAS-CHAVE: lazer – cultura – educação – Educação Física – academias de ginástica. This text presents an investigation about the characteristics and trends in flexible accumulation that push de development of the fitness market. This study examines the case of Curves Brasil. To do so, we tried to confront and examine the implementation of organizational techniques with tested efficacy in a global scale through the verification of a particular and real case of development. Our conclusions point to new innovation techniques being currently used to solve the difficult equation faced by this sector with regards to attracting and retaining customers. KEYWORDS: leisure – culture – education – Physical Education – gyms. Este texto presenta los resultados de una investigación relativa a las características y las tendencias de la acumulación flexible que engloban el desarrollo del mercado Del fitness. Se trata de un estudio de caso de Curves Brasil, para el cual buscamos enfrentar y examinar la implantación de técnicas organizacionales que han evidenciado ya eficacia en escala mundial con el principio de la verificación de un caso particular y real de desarrollo. Las conclusiones señalan nuevas técnicas de innovación utilizadas para resolver la difícil ecuación que hecha frente al sector
Duval, M; Guilarte Moreno, V; Grün, R
2013-12-01
This work deals with the specific studies of three main sources of uncertainty in electron spin resonance (ESR) dosimetry/dating of fossil tooth enamel: (1) the precision of the ESR measurements, (2) the long-term signal fading the selection of the fitting function. They show a different influence on the equivalent dose (D(E)) estimates. Repeated ESR measurements were performed on 17 different samples: results show a mean coefficient of variation of the ESR intensities of 1.20 ± 0.23 %, inducing a mean relative variability of 3.05 ± 2.29 % in the D(E) values. ESR signal fading over 5 y was also observed: its magnitude seems to be quite sample dependant but is nevertheless especially important for the most irradiated aliquots. This fading has an apparent random effect on the D(E) estimates. Finally, the authors provide new insights and recommendations about the fitting of ESR dose-response curves of fossil enamel with a double saturating exponential (DSE) function. The potential of a new variation of the DSE was also explored. Results of this study also show that the choice of the fitting function is of major importance, maybe more than the other sources previously mentioned, in order to get accurate final D(E) values.
Konzen, Kevin; Brey, Richard
2012-05-01
²²²Rn (radon) and ²²⁰Rn (thoron) progeny are known to interfere with determining the presence of long-lived transuranic radionuclides, such as plutonium and americium, and require from several hours up to several days for conclusive results. Methods are proposed that should expedite the analysis of air samples for determining the amount of transuranic radionuclides present using low-resolution alpha spectroscopy systems available from typical alpha continuous air monitors (CAMs) with multi-channel analyzer (MCA) capabilities. An alpha spectra simulation program was developed in Microsoft Excel visual basic that employed the use of Monte Carlo numerical methods and serial-decay differential equations that resembled actual spectra. Transuranic radionuclides were able to be quantified with statistical certainty by applying peak fitting equations using the method of least squares. Initial favorable results were achieved when samples containing radon progeny were decayed 15 to 30 min, and samples containing both radon and thoron progeny were decayed at least 60 min. The effort indicates that timely decisions can be made when determining transuranic activity using available alpha CAMs with alpha spectroscopy capabilities for counting retrospective air samples if accompanied by analyses that consider the characteristics of serial decay.
Indian Academy of Sciences (India)
S Chatterjee; V C Vani
2005-09-01
In the context of scattering of light, we determine the extent of randomness within which a hidden periodic part can still be detected. The detection is carried out using a technique called the extended matched filtering, first introduced by us in this context. The earlier prediction, before our technique was introduced, had placed the limit of detection, by intensity measurements alone, at (0/) ∼ 0.33, where 0 is the coherence length of light for scattering by the rough part of the surface and is the wavelength of the periodic part of the surface. In our earlier works we have shown that by intensity measurements alone, the limit of detection can be taken to a much lower value of (0/), when the extended matched filtering method is employed. In this paper we follow the extended matched filtering method, and try to reach the lowest possible value of detection in (0/) by fitting the data to a polynomial. It is concluded by our numerical work that the lowest possible limit for detection from intensity measurements alone is (0/) = 0.11.
Chow, Sy-Miin; Lu, Zhaohua; Sherwood, Andrew; Zhu, Hongtu
2016-03-01
The past decade has evidenced the increased prevalence of irregularly spaced longitudinal data in social sciences. Clearly lacking, however, are modeling tools that allow researchers to fit dynamic models to irregularly spaced data, particularly data that show nonlinearity and heterogeneity in dynamical structures. We consider the issue of fitting multivariate nonlinear differential equation models with random effects and unknown initial conditions to irregularly spaced data. A stochastic approximation expectation-maximization algorithm is proposed and its performance is evaluated using a benchmark nonlinear dynamical systems model, namely, the Van der Pol oscillator equations. The empirical utility of the proposed technique is illustrated using a set of 24-h ambulatory cardiovascular data from 168 men and women. Pertinent methodological challenges and unresolved issues are discussed.
Institute of Scientific and Technical Information of China (English)
Jesus Mellado; Edgar Sepulveda; Jose E Garcia; Alvaro Rodriguez; Maria A De Santiago; Francisco G Veliz; Miguel Mellado
2014-01-01
artiifcial lactation, which would imply an overall reduction in voluntary culling of cows. Also, various equations used to describe the lactation curves demonstrated the potential for iftting monthly milk records of Holstein cows with prolonged lactations and induced hormonally into lactation.
Moshirfar, Majid; Calvo, Charles M; Kinard, Krista I; Williams, Lloyd B; Sikder, Shameema; Neuffer, Marcus C
2011-01-01
This study analyzes the characteristics of donor and recipient tissue preparation between the Hessburg-Barron and Hanna punch and trephine systems by using elliptical curve fitting models, light microscopy, and anterior segment optical coherence tomography (AS-OCT). Eight millimeter Hessburg-Barron and Hanna vacuum trephines and punches were used on six cadaver globes and six corneal-scleral rims, respectively. Eccentricity data were generated using measurements from photographs of the corneal buttons and were used to generate an elliptical curve fit to calculate properties of the corneal button. The trephination angle and punch angle were measured by digital protractor software from light microscopy and AS-OCT images to evaluate the consistency with which each device cuts the cornea. The Hanna trephine showed a trend towards producing a more circular recipient button than the Barron trephine (ratio of major axis to minor axis), ie, 1.059 ± 0.041 versus 1.110 ± 0.027 (P = 0.147) and the Hanna punch showed a trend towards producing a more circular donor cut than the Barron punch, ie, 1.021 ± 0.022 versus 1.046 ± 0.039 (P = 0.445). The Hanna trephine was demonstrated to have a more consistent trephination angle than the Barron trephine when assessing light microscopy images, ie, ±14.39° (95% confidence interval [CI] 111.9-157.7) versus ±19.38° (95% CI 101.9-150.2, P = 0.492) and OCT images, ie, ±8.08° (95% CI 106.2-123.3) versus ±11.16° (95% CI 109.3-132.6, P = 0.306). The angle created by the Hanna punch had less variability than the Barron punch from both the light microscopy, ie, ±4.81° (95% CI 101.6-113.9) versus ±11.28° (95% CI 84.5-120.6, P = 0.295) and AS-OCT imaging, ie, ±9.96° (95% CI 95.7-116.4) versus ±14.02° (95% CI 91.8-123.7, P = 0.825). Statistical significance was not achieved. The Hanna trephine and punch may be more accurate and consistent in cutting corneal buttons than the Hessburg-Barron trephine and punch when evaluated using
Moshirfar, Majid; Calvo, Charles M; Kinard, Krista I; Williams, Lloyd B; Sikder, Shameema; Neuffer, Marcus C
2011-01-01
Background: This study analyzes the characteristics of donor and recipient tissue preparation between the Hessburg-Barron and Hanna punch and trephine systems by using elliptical curve fitting models, light microscopy, and anterior segment optical coherence tomography (AS-OCT). Methods: Eight millimeter Hessburg-Barron and Hanna vacuum trephines and punches were used on six cadaver globes and six corneal-scleral rims, respectively. Eccentricity data were generated using measurements from photographs of the corneal buttons and were used to generate an elliptical curve fit to calculate properties of the corneal button. The trephination angle and punch angle were measured by digital protractor software from light microscopy and AS-OCT images to evaluate the consistency with which each device cuts the cornea. Results: The Hanna trephine showed a trend towards producing a more circular recipient button than the Barron trephine (ratio of major axis to minor axis), ie, 1.059 ± 0.041 versus 1.110 ± 0.027 (P = 0.147) and the Hanna punch showed a trend towards producing a more circular donor cut than the Barron punch, ie, 1.021 ± 0.022 versus 1.046 ± 0.039 (P = 0.445). The Hanna trephine was demonstrated to have a more consistent trephination angle than the Barron trephine when assessing light microscopy images, ie, ±14.39° (95% confidence interval [CI] 111.9–157.7) versus ±19.38° (95% CI 101.9–150.2, P = 0.492) and OCT images, ie, ±8.08° (95% CI 106.2–123.3) versus ±11.16° (95% CI 109.3–132.6, P = 0.306). The angle created by the Hanna punch had less variability than the Barron punch from both the light microscopy, ie, ±4.81° (95% CI 101.6–113.9) versus ±11.28° (95% CI 84.5–120.6, P = 0.295) and AS-OCT imaging, ie, ±9.96° (95% CI 95.7–116.4) versus ±14.02° (95% CI 91.8–123.7, P = 0.825). Statistical significance was not achieved. Conclusion: The Hanna trephine and punch may be more accurate and consistent in cutting corneal buttons than
疲劳S-N曲线的加权最小二乘法拟合%WEIGHTED LEAST SQUARE METHOD FOR S-N CURVE FITTING
Institute of Scientific and Technical Information of China (English)
吉凤贤; 姚卫星
2004-01-01
提出了一种拟合材料疲劳S-N曲线的加权最小二乘法,各应力水平下的拟合点的权重反比于均值置信区间的长度.两个算例结果表明:本文方法较好地考虑了S-N曲线分散性的物理特性.%An S-N curve fitting approach is proposed based on the weighted least square method, and the weights are inversely proportional to the length of mean confidence intervals of experimental data sets. The assumption coincides with the physical characteristics of the fatigue life scatter. Two examples demonstrate the method. It is shown that the method has better accuracy and reasonableness compared with the usual least square method.
基于曲线拟合优化设计肋片管换热器%Using Curve Fitting to Optimize of Fin and Tube Heat Exchanger
Institute of Scientific and Technical Information of China (English)
杨恒; 朱梅; 远高
2013-01-01
主要对等厚环肋传热过程进行数值分析，利用曲线拟合的方法计算不同肋片尺寸下的散热量和肋效率的精确解，并在金属消耗一定和散热量一定情况下，优化等厚环肋的结构。% This thesis discusses numerical analysis the process of heat transfer by uniform annular fin, using the curve fitting method to calculate the exact solution of heat transfer and fin sufficiency under the different fin sizes, and optimize of the structure of the uniform annular fin based on the same metal consumption and the same heat transfer of a single fin.
Hu, Y. J.; Yang, J.; Kitipornchai, S.
2013-07-01
This paper presents a geometrically nonlinear micro-beam model for the electro-dynamic analysis of an initially curved micro-beam under an applied voltage, with an emphasis on its snap-through and pull-in behaviors. The governing equations of motion and the associated boundary conditions are derived in an arc coordinate system without involving any assumptions on the nonlinear deformation. Differential quadrature method (DQM) and Petzold-Gear Backward Differentiation Formulas (BDF) are employed to solve the governing equations in the space and time domains respectively to obtain the nonlinear fundamental frequency, snap-through voltage, pull-in voltage and the corresponding mode shapes of a micro-beam clamped at both ends. The present analysis is validated through a direct comparison with the published experimental and numerical results. A parametric study is conducted to investigate the influences of the initial gap, base length, arc rise, and initial curved configuration on the snap-through and pull-in behaviors of the micro-beam.
Lin, Shan-Yang; Lin, Hong-Liang; Chi, Ying-Ting; Huang, Yu-Ting; Kao, Chi-Yu; Hsieh, Wei-Hsien
2015-12-30
The amorphous form of a drug has higher water solubility and faster dissolution rate than its crystalline form. However, the amorphous form is less thermodynamically stable and may recrystallize during manufacturing and storage. Maintaining the amorphous state of drug in a solid dosage form is extremely important to ensure product quality. The purpose of this study was to quantitatively determine the amount of amorphous indomethacin (INDO) formed in the Soluplus® solid dispersions using thermoanalytical and Fourier transform infrared (FTIR) spectral curve-fitting techniques. The INDO/Soluplus® solid dispersions with various weight ratios of both components were prepared by air-drying and heat-drying processes. A predominate IR peak at 1683cm(-1) for amorphous INDO was selected as a marker for monitoring the solid state of INDO in the INDO/Soluplus® solid dispersions. The physical stability of amorphous INDO in the INDO/Soluplus® solid dispersions prepared by both drying processes was also studied under accelerated conditions. A typical endothermic peak at 161°C for γ-form of INDO (γ-INDO) disappeared from all the differential scanning calorimetry (DSC) curves of INDO/Soluplus® solid dispersions, suggesting the amorphization of INDO caused by Soluplus® after drying. In addition, two unique IR peaks at 1682 (1681) and 1593 (1591)cm(-1) corresponded to the amorphous form of INDO were observed in the FTIR spectra of all the INDO/Soluplus® solid dispersions. The quantitative amounts of amorphous INDO formed in all the INDO/Soluplus® solid dispersions were increased with the increase of γ-INDO loaded into the INDO/Soluplus® solid dispersions by applying curve-fitting technique. However, the intermolecular hydrogen bonding interaction between Soluplus® and INDO were only observed in the samples prepared by heat-drying process, due to a marked spectral shift from 1636 to 1628cm(-1) in the INDO/Soluplus® solid dispersions. The INDO/Soluplus® solid
Directory of Open Access Journals (Sweden)
Paula Machado dos Santos
2007-12-01
Full Text Available O ajuste de curvas de crescimento de plantas de alface durante seu ciclo necessita de amostragens no tempo, o que restringe o número de efeitos de tratamentos estudados. Com o objetivo de determinar o cronograma de amostragem de plantas de alface em hidroponia para o ajuste de curvas de crescimento até a fase de maturação das sementes, foram realizados dois cultivos em casa de vegetação durante a primavera e o outono, em área pertencente ao Departamento de Fitotecnia, na UFSM, Santa Maria, RS. A partir do ajuste de um modelo de crescimento com amostragem diária, simularam-se diferentes cronogramas de amostragem para o ajuste do mesmo modelo. Para encontrar o cronograma de maior intervalo entre amostragens, ou seja, menor número de coletas, foi comparado o ajuste do modelo de amostragem diária com os ajustes dos modelos dos diferentes intervalos de amostragens simulados, dois a dois, pelo teste F. Foram realizadas simulações considerando desde a data de transplante até a produção de sementes, para variáveis de fitomassa seca da planta e de partes da planta e área foliar. Em experimentos realizados com alface hidropônica na primavera, para o ciclo completo, recomendam-se amostragens a cada 3, 8, 20 e 9 dias para fitomassa seca relativa total da planta de alface, de folhas, de raiz e área foliar, respectivamente; enquanto que, para experimentos realizados no outono, é recomendável utilizar intervalos de amostragens a cada 2, 11, 12 e 11 dias, respectivamente.The fitting of growth curves for lettuce plants requires many samplings within o time interval, while can restrict the number of studied treatments. With the aim o determine sampling chronogram hidroponic lettuce for the fitting of growth curves until maturation of seeds. Two greenhouse trials were carried out in spring an autumn, at UFSM experimental area, Santa Maria, RS. Different sampling interval were simulated using the fitting of a daily model. The optimum sampling
Sakurai-Yageta, Mika; Maruyama, Tomoko; Suzuki, Takashi; Ichikawa, Kazuhisa; Murakami, Yoshinori
2015-01-01
Protein components of cell adhesion machinery show continuous renewal even in the static state of epithelial cells and participate in the formation and maintenance of normal epithelial architecture and tumor suppression. CADM1 is a tumor suppressor belonging to the immunoglobulin superfamily of cell adhesion molecule and forms a cell adhesion complex with an actin-binding protein, 4.1B, and a scaffold protein, MPP3, in the cytoplasm. Here, we investigate dynamic regulation of the CADM1-4.1B-MPP3 complex in mature cell adhesion by fluorescence recovery after photobleaching (FRAP) analysis. Traditional FRAP analysis were performed for relatively short period of around 10 min. Here, thanks to recent advances in the sensitive laser detector systems, we examine FRAP of CADM1 complex for longer period of 60 min and analyze the recovery with exponential curve-fitting to distinguish the fractions with different diffusion constants. This approach reveals that the fluorescence recovery of CADM1 is fitted to a single exponential function with a time constant (τ) of approximately 16 min, whereas 4.1B and MPP3 are fitted to a double exponential function with two τs of approximately 40-60 sec and 16 min. The longer τ is similar to that of CADM1, suggesting that 4.1B and MPP3 have two distinct fractions, one forming a complex with CADM1 and the other present as a free pool. Fluorescence loss in photobleaching analysis supports the presence of a free pool of these proteins near the plasma membrane. Furthermore, double exponential fitting makes it possible to estimate the ratio of 4.1B and MPP3 present as a free pool and as a complex with CADM1 as approximately 3:2 and 3:1, respectively. Our analyses reveal a central role of CADM1 in stabilizing the complex with 4.1B and MPP3 and provide insight in the dynamics of adhesion complex formation.
Directory of Open Access Journals (Sweden)
Moshirfar M
2011-08-01
Full Text Available Majid Moshirfar1, Charles M Calvo2, Krista I Kinard1, Lloyd B Williams1, Shameema Sikder3, Marcus C Neuffer11University of Utah, Department of Ophthalmology and Visual Sciences, Salt Lake City, UT, USA; 2University of Nevada, School of Medicine, Las Vegas, NV, USA; 3Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USABackground: This study analyzes the characteristics of donor and recipient tissue preparation between the Hessburg-Barron and Hanna punch and trephine systems by using elliptical curve fitting models, light microscopy, and anterior segment optical coherence tomography (AS-OCT.Methods: Eight millimeter Hessburg-Barron and Hanna vacuum trephines and punches were used on six cadaver globes and six corneal-scleral rims, respectively. Eccentricity data were generated using measurements from photographs of the corneal buttons and were used to generate an elliptical curve fit to calculate properties of the corneal button. The trephination angle and punch angle were measured by digital protractor software from light microscopy and AS-OCT images to evaluate the consistency with which each device cuts the cornea.Results: The Hanna trephine showed a trend towards producing a more circular recipient button than the Barron trephine (ratio of major axis to minor axis, ie, 1.059 ± 0.041 versus 1.110 ± 0.027 (P = 0.147 and the Hanna punch showed a trend towards producing a more circular donor cut than the Barron punch, ie, 1.021 ± 0.022 versus 1.046 ± 0.039 (P = 0.445. The Hanna trephine was demonstrated to have a more consistent trephination angle than the Barron trephine when assessing light microscopy images, ie, ±14.39° (95% confidence interval [CI] 111.9–157.7 versus ±19.38° (95% CI 101.9–150.2, P = 0.492 and OCT images, ie, ± 8.08° (95% CI 106.2–123.3 versus ± 11.16° (95% CI 109.3–132.6, P = 0.306. The angle created by the Hanna punch had less variability than the Barron punch from both the light microscopy
Akhunov, T. A.; Wertz, O.; Elyiv, A.; Gaisin, R.; Artamonov, B. P.; Dudinov, V. N.; Nuritdinov, S. N.; Delvaux, C.; Sergeyev, A. V.; Gusev, A. S.; Bruevich, V. V.; Burkhonov, O.; Zheleznyak, A. P.; Ezhkova, O.; Surdej, J.
2017-03-01
We present new photometric observations of H1413+117 acquired during seasons between 2001 and 2008 in order to estimate the time delays between the lensed quasar images and to characterize at best the on-going micro-lensing events. We propose a highly performing photometric method called the adaptive point spread function fitting and have successfully tested this method on a large number of simulated frames. This has enabled us to estimate the photometric error bars affecting our observational results. We analysed the V- and R-band light curves and V-R colour variations of the A-D components which show short- and long-term brightness variations correlated with colour variations. Using the χ2 and dispersion methods, we estimated the time delays on the basis of the R-band light curves over the seasons between 2003 and 2006. We have derived the new values: ΔtAB = -17.4 ± 2.1, ΔtAC = -18.9 ± 2.8 and ΔtAD = 28.8 ± 0.7 d using the χ2 method (B and C are leading, D is trailing) with 1σ confidence intervals. We also used available observational constraints (resp. the lensed image positions, the flux ratios in mid-IR and two sets of time delays derived in the present work) to update the lens redshift estimation. We obtained z_l = 1.95^{+0.06}_{-0.10} which is in good agreement with previous estimations. We propose to characterize two kinds of micro-lensing events: micro-lensing for the A, B, C components corresponds to typical variations of ∼10-4 mag d-1 during all the seasons, while the D component shows an unusually strong micro-lensing effect with variations of up to ∼10-3 mag d-1 during 2004 and 2005.
三相异步电机空载试验特性曲线拟合%Characteristic curve-fitting of ho-load test for three-phase asynchronous motor
Institute of Scientific and Technical Information of China (English)
刘鹏; 郭颖达; 王志芳
2011-01-01
Data processing of motor type test has a problem of low precision of curve-fitting. This paper proposed a curve-fitting function and made a detailed discussion on how to discriminate original data and the function that fits no-load test. VC++ language is adopted to realize data discrimination and draw a characteristic curve of high precision.%针对处理电机试验数据时曲线拟合精度低的情况,提出了空载试验的拟合函数.详细讨论了对原始数据的甄别,以及适用于空载试验的函数,采用VC++实现数据甄别,绘制精度高的特性曲线.
不同性别黑番鸭生长曲线的拟合和分析%Analysis and Fitting of Growth Curve in Different Sexual Black Muscovy
Institute of Scientific and Technical Information of China (English)
朱志明; 黄种彬; 钟志新; 缪中纬; 陈晖; 郑嫩珠
2011-01-01
As the black Muscovy for experimental material, the early bodyweight of different sexual black Muscovy from 0 to 10 weeks old were measured, in order to investigate the growth model in this study, three kinds of nonlinear models of Gompertz, Logistic and von Bertalanffy were used to fit the growth curve respectively. The results showed that black Muscovy grew slowly before age of 4 weeks, the growth rate accelerated significantly after age of 4 weeks, and reached the growth peak at age of 6 to 10 weeks. Compared with goodness of fit (R2), the results showed the growth curve could be well fitted with these three models and the R2 was above 0. 99, but the Gompertz model had well closed to the actual observed values . Further more, the fitting parameters of Gompertz model between genders were compared, and the male black Muscovy showed higher initial weight, maximum bodyweight, and inflection point weight than female black Muscovy. The inflection age of male was 5. 3 weeks and the female was 4. 3 weeks. The Gomperte model equation for male and female black muscovy was W=3111. 4 [exp - 4. 4482exp (- 0. 2802t)] and W=2100. 4 [exp-4. 1071exp ( - 0. 32250] respectively. This study would help to understand the growth model and development of different sexual black Muscovy, and would provide the scientific basis for rational use of resources, breeding germplasm and selection in black Muscovy.%以黑番鸭为试验材料,测定了不同性别黑番鸭从初生到10周龄的体重,用Gompertz、Logistic、von Bertalanffy 3种非线性生长模型拟合其生长曲线,研究不同性别黑番鸭生长模式的差异.结果表明:公、母黑番鸭在4周龄前生长较为缓慢,4周龄后生长速度开始明显加快,在6～10周龄达到生长高峰.通过比较拟合度(R2)发现3种曲线模型拟合度均达到0.99以上,但Gompertz模型的拟合结果更接近于实际测量值,拟合效果最佳.进一步比较不同性别黑番鸭Gompertz模型拟合参数,结果发
Optimum Theory of Fitting-curve with Minimum Error of Radius%曲率半径误差最小的曲线拟合优化方法
Institute of Scientific and Technical Information of China (English)
钟汉桥; 唐晓腾; 叶仲和
2001-01-01
Analysis the defaults of the fitting-curve at present, find a optimum theory of fitting-curve with the minimum error of the radius is indicated,and its feasibility is proved by samples.%分析并指出了现行各种曲线拟合方法的缺陷，提出了一种以曲率半径误差最小为原则的双圆弧拟合曲线的优化方法,通过实例验证了这种新型方法的可行性。
Energy Technology Data Exchange (ETDEWEB)
Chang, Liyun, E-mail: cliyun2000@gmail.com [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Ho, Sheng-Yow [Department of Radiation Oncology, Chi Mei Medical Center, Liouying, Tainan, Taiwan (China); Lee, Tsair-Fwu [Medical Physics and Informatics Laboratory, Department of Electronics Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan (China); Yeh, Shyh-An [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Department of Radiation Oncology, E-Da Hospital, Kaohsiung, Taiwan (China); Ding, Hueisch-Jy [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Chen, Pang-Yu, E-mail: pangyuchen@yahoo.com.tw [Department of Radiation Oncology, Sinlau Christian Hospital, Tainan, Taiwan (China)
2015-03-21
EBT2 film is a convenient dosimetry quality-assurance (QA) tool with high 2D dosimetry resolution and a self-development property for use in verifications of radiation therapy treatment planning and special projects; however, the user will suffer from a relatively higher degree of uncertainty (more than ±6% by Hartmann et al. [29]), and the trouble of cutting one piece of film into small pieces and then reintegrating them each time. To prevent this tedious cutting work, and save calibration time and budget, a dose range analysis is presented in this study for EBT2 film calibration using the Percentage–Depth–Dose (PDD) method. Different combinations of the three dose ranges, 9–26 cGy, 33–97 cGy and 109–320 cGy, with two types of curve fitting algorithms, film pixel values and net optical densities converting into doses, were tested and compared. With the lowest error and acceptable inaccuracy of less than 3 cGy for the clinical dose range (9–320 cGy), a single film calibrated by the net optical density algorithm with the dose range 109–320 cGy was suggested for routine calibration.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We introduce a new method to derive the orbital parameters of spectroscopic binary stars by nonlinear least squares of (o - c). Using the measured radial velocity data of the four double lined spectroscopic binary systems,AI Phe,GM Dra,HD 93917 and V502 Oph,we derived both the orbital and combined spectroscopic elements of these systems.Our numerical results are in good agreement with the those obtained using the method of Lehmann-Filhés.
Liebowitz, H.; Jones, D. L.; Poulose, P. K.
1974-01-01
Because of the current high degree of interest in the development of a standard nonlinear test method, analytical and experimental comparisons have been made between the R-curve, COD, J-integral and nonlinear energy methods. A general definition of fracture toughness is proposed and the fundamental definitions of each method are compared to it. Experimental comparisons between the COD, J-integral, nonlinear energy and standard ASTM methods have been made for a series of compact tension tests on several aluminum alloys. Some of the tests were conducted according to the ASTM standard method E399-72, while the specimen thickness was reduced below the minimum requirement for plane strain fracture toughness testing for several other test series. The fracture toughness values obtained by the COD method were significantly higher than the toughness values obtained by the other three methods. All of the methods displayed a tendency to yield higher toughness values as the thickness was decreased below the ASTM plane strain requirement.
三次B样条曲线拟合的虹膜定位%Iris Localization Algorithm Based on Cubic B-spline Curve Fitting
Institute of Scientific and Technical Information of China (English)
叶永强; 沈建新; 周啸; 张敏
2011-01-01
采用圆检测定位虹膜内外边界的方法是当前虹膜定位的主流算法.当虹膜图像分辨率很高时,圆曲线不能准确地拟合虹膜真实边界,特别是受瞳孔收缩影响很大的内边界.而采用三次B样条曲线能够很好地拟合内边界.为了提高定位效率,首先运用质心探测方法分割出瞳孔区域,然后在瞳孔区域中搜索内边界点,采用三次B样条曲线精确拟合内边界；最后利用Canny算子检测外边界,并采用圆曲线的最小二乘拟合外边界.运用Bath大学虹膜库中的1000幅虹膜图像对该定位算法进行测试,内边界定位时间0.0203s、准确率99.2％；外边界定位时间2.0277s,准确率98.9％,满足准确、高效的定位要求.%The current important methods of iris localization are based on circle detection. But they could not fit the real boundary well when iris images are high-resolution, especially the inner boundary under the influence of pupil constriction. Proposed method based on cubic B-spline curve can figure out this problem. It locates the inner boundary area first, and then the outer boundary. To improve the efficiency and robustness for inner boundary localization, this paper has proposed a method to segment the pupil area first based centroid detection, then search inner edge in the segmented area. The outer boundary area is then determined by using Ihe parameter relations between inner and outer boundary. Finally, using canny operator delects the outer edge, and the outer boundary is fitted in the Least-square circle sense. The Experiment results based on the iris database of Bath University, with 99.2% accuracy and 0.022s positioning time of inner boundary, 98.9% and 2.027s of outer show that the proposed approach is efficient and robust.
Curved Surface Fitting in the Application of the GPS Coordinate Transformation%曲面拟合在 GPS 坐标转换中的应用
Institute of Scientific and Technical Information of China (English)
吕红涛; 左海玉; 方广杰
2015-01-01
GPS由于其高精度、速度快、全天候的特点，在工程测量及城市工程网的建立、更新和改造中广泛应用。但是GPS测量结果为WGS－84坐标，而实际应用的坐标系往往是1954北京坐标系和1980西安坐标系。本文针对GPS坐标转换过程中由于利用公共点求解转换参数，而将原有坐标系中系统误差引入转换过程中的情况，探讨将曲面拟合法应用到坐标转换中来处理转换残差的可行性，并通过工程实例证明了该方法可行。%Because the technology of GPS position has the prominent advantages of high precision, fast speed and all-weather, it is widely used in the engineering survey and setting-up, upgrading and transforming of the urban engineering work.However, the GPS measurement result in the WGS -84 coordinate, and the practical application of the coordinate system is often BJ -54 coordinate system and the Xi’ an 80 coordinate system. In this paper, aims at the use of public point of solving the transformation parameters in the process of GPS coordinates conversion, and introducing system error in the original coordinate system to the process of transforma-tion, to explore the feasibility of application of curved surface fitting method in coordinate transformation to deal with the transformation residual, and through the engineering example proves the feasibility of this method.
Non-linear Growth Models in Mplus and SAS.
Grimm, Kevin J; Ram, Nilam
2009-10-01
Non-linear growth curves or growth curves that follow a specified non-linear function in time enable researchers to model complex developmental patterns with parameters that are easily interpretable. In this paper we describe how a variety of sigmoid curves can be fit using the Mplus structural modeling program and the non-linear mixed-effects modeling procedure NLMIXED in SAS. Using longitudinal achievement data collected as part of a study examining the effects of preschool instruction on academic gain we illustrate the procedures for fitting growth models of logistic, Gompertz, and Richards functions. Brief notes regarding the practical benefits, limitations, and choices faced in the fitting and estimation of such models are included.
Institute of Scientific and Technical Information of China (English)
张晓星; 谢颜斌; 姚尧
2008-01-01
The SF6 decomposed products are very alike, so the peaks of the SF6 decomposed products are overlapped. It make us hard to quantitatively calculate. This paper introduced a method to separate the overlapped chromatogram peaks with iterative curve-fitting and Gauss function, and deduced the formula of the iterative curve-fitting;provided a method to calculate the initial value of the peaks intensity and width by iterative formula, and confirm the final peaks intensity and width to separate the overlapped signals. By the analysis of the real chromatogram data, it proved the validity of this method on the main components used in distinguishing the GIS internal defects. This method overcomes the influence of SF6 peak to the other thin concentration peaks, so it can be used in the study of the quantitative analysis of the decomposed products on different failures and different voltages.
Institute of Scientific and Technical Information of China (English)
于惠; 刘真
2011-01-01
各单色通道保持线性输出是喷墨打印机线性化校正的前提，以LSM（最小二乘法）的不足为启示，分析了LSM分段拟合技术的原理及特点，进而提出了针对图像的不同色调采用LSM分段拟合技术。实验分别采用LSM分段拟合技术和普通LSM拟合技术，拟合了喷墨打印机的反补偿曲线，再打印出反馈的应输入控制信息，最终评价比较了2种曲线模型下的输出样稿效果。结果表明：最小二乘法分段曲线拟合技术比普通最小二乘拟合技术更适用于喷墨输出反馈控制过程中。%Precise inking of every channel is the presupposition of inkjet printers＇ linearization. The principle and feature of LSM piece wise curve-fitting technology was analyzed. Pictures＂ different tones were treated with LSM piece wise Printing feedback controlling curve was fitted with LSM piece wise curve-fitting technology and common LSM curve-fitting technology. Sample sheets printed by the two control technologies were evaluated and compared. The results showed that LSM Piece Wise method is more suitable for the inkier printers＇ feed back control.
Energy Technology Data Exchange (ETDEWEB)
Heasler, Patrick G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Michael T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Doctor, Steven R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2016-09-20
The NRC, in cooperation with industry, is developing a computerized simulation and analytical tool within the Extremely Low Probability of Rupture (xLPR) Project to provide insights for determining whether certain types of service degradation would be expected to challenge safety-related systems at operating nuclear power plants. One input for this tool is the probability of detection (POD) for the nondestructive examinations conducted during inservice inspections at these plants. EPRI produced a series of POD curves for ultrasonic testing with data from the industry’s Performance Demonstration Initiative. This report compares the POD curves developed from the EPRI data to other relevant attempts to quantify POD on similar component configurations. The objectives of this report are 1) to determine the reasonableness of the EPRI curves and 2) attempt to explain discrepancies noted with other recent POD studies.
Vriens, D.; Geus-Oei, L.F. de; Oyen, W.J.G.; Visser, E.P.
2009-01-01
For the quantification of dynamic (18)F-FDG PET studies, the arterial plasma time-activity concentration curve (APTAC) needs to be available. This can be obtained using serial sampling of arterial blood or an image-derived input function (IDIF). Arterial sampling is invasive and often not feasible i
Directory of Open Access Journals (Sweden)
Marcelo Maia Pereira
2014-12-01
Full Text Available Knowledge of the growth of animals is important so that zootechnical activity can be more accurate and sustainable. The objective of this study was to describe the live weight, development of liver tissue and fat body, leg growth, and cumulative food intake of bullfrogs during the fattening phase using nonlinear models. A total of 2,375 bullfrog froglets with an initial weight of 7.03 ± 0.16 g were housed in five fattening pens (12 m². Ten samplings were performed at intervals of 14 days to obtain the variables studied. These data were used to estimate the parameters of Gompertz and logistic models as a function of time. The estimated values of weight (Wm and food intake (FIm at maturity and time when the growth rate is maximum (t* were closer to expected values when the logistic model was used. The Wm values for live weight and liver, adipose and leg weights and the FIm value for food intake were 343.7, 15.7, 19.6, 96.03 and 369.3 g, respectively, with t* at 109, 98, 105, 109 and 107 days. Therefore, the logistic model was the best model to estimate the growth and food intake of bullfrogs during the fattening phase.
Institute of Scientific and Technical Information of China (English)
王丽丽; 张景绘
2001-01-01
利用非平稳信号的时频分析方法研究了一类非线性系统的频率特性和阻尼特性随运动形态的变化规律，得到了能简洁、直观地反映系统基本非线性动力学特性的广义骨架线性系统(简称GSLS)和骨架曲线,在此基础上，利用时频滤波方法根据系统非平稳响应信号对非线性系统进行辨识,该项工作为非线性系统反问题的研究提供了一条新的途径,%The nonlinear behavior varying with the instantaneous response was analyzed through the joint time_frequency analysis method for a class of S.D.O.F nonlinear system. A masking operator on definite regions is defined and two theorems are presented. Based on these, the nonlinear system is modeled with a special time_varying linear one, called the generalized skeleton linear system(GSLS). The frequency skeleton curve and the damping skeleton curve are defined to describe the main feature of the non_linearity as well. Moreover, an identification method is proposed through the skeleton curves and the time_frequency filtering technique.
Biomedical model fitting and error analysis.
Costa, Kevin D; Kleinstein, Steven H; Hershberg, Uri
2011-09-20
This Teaching Resource introduces students to curve fitting and error analysis; it is the second of two lectures on developing mathematical models of biomedical systems. The first focused on identifying, extracting, and converting required constants--such as kinetic rate constants--from experimental literature. To understand how such constants are determined from experimental data, this lecture introduces the principles and practice of fitting a mathematical model to a series of measurements. We emphasize using nonlinear models for fitting nonlinear data, avoiding problems associated with linearization schemes that can distort and misrepresent the data. To help ensure proper interpretation of model parameters estimated by inverse modeling, we describe a rigorous six-step process: (i) selecting an appropriate mathematical model; (ii) defining a "figure-of-merit" function that quantifies the error between the model and data; (iii) adjusting model parameters to get a "best fit" to the data; (iv) examining the "goodness of fit" to the data; (v) determining whether a much better fit is possible; and (vi) evaluating the accuracy of the best-fit parameter values. Implementation of the computational methods is based on MATLAB, with example programs provided that can be modified for particular applications. The problem set allows students to use these programs to develop practical experience with the inverse-modeling process in the context of determining the rates of cell proliferation and death for B lymphocytes using data from BrdU-labeling experiments.
GP2D12红外测距传感器曲线拟合函数设计%Design Research of GP2D12 IR Distance Measuring Sensor Curve Fitting Function
Institute of Scientific and Technical Information of China (English)
彭伟
2012-01-01
GP2D12是SHAR P公司一种新型的红外测距传感器。ACR ONAME R OBOTICS基于最小二乘原理提出了以乘幂函数为模型的两种曲线拟合设计方法,使用拟合函数编写了微控制器C程序,在嵌入式测距系统电路中实测运行,实现了稳定的高精度测距效果。%Research and propose an improvement design on the generating method of GP2D12 infrared distance sensor curve fitting function which proposed by Acroname Robotics,based on the least squares principle we use power function as a model propose an design method of two kinds of curve fitting,by using the fitting function we design a microcontroller C procedures and achieve a stable high accuracy distance measuring effects when operating it in the embedded system circuit.
Directory of Open Access Journals (Sweden)
Sutawanir Darwis
2012-05-01
Full Text Available Empirical decline curve analysis of oil production data gives reasonable answer in hyperbolic type curves situations; however the methodology has limitations in fitting real historical production data in present of unusual observations due to the effect of the treatment to the well in order to increase production capacity. The development ofrobust least squares offers new possibilities in better fitting production data using declinecurve analysis by down weighting the unusual observations. This paper proposes a robustleast squares fitting lmRobMM approach to estimate the decline rate of daily production data and compares the results with reservoir simulation results. For case study, we usethe oil production data at TBA Field West Java. The results demonstrated that theapproach is suitable for decline curve fitting and offers a new insight in decline curve analysis in the present of unusual observations.
Olspert, Nigul; Pelt, Jaan; Cole, Elizabeth M; Hackman, Thomas; Lehtinen, Jyri; Henry, Gregory W
2014-01-01
We study LQ Hya photometry for 1982-2014 with the carrier fit (CF) -method and compare our results to earlier photometric analysis and recent Doppler imaging maps. We first utilize different types of statistical methods to estimate various candidates for the carrier period for the CF method. Secondly, a global fit to the whole data set and local fits to shorter segments are computed with the period that is found to be the optimal one. The harmonic least-squares analysis of all the available data reveals a short period close to 1.6 days as a limiting value for a set of significant frequencies. We interpret this as the rotation period of the spots near the equatorial region. In addition, the distribution of the significant periods is found to be bimodal, hinting of a longer-term modulating period, which we set out to study with a two-harmonic CF model. Weak modulation signal is, indeed retrieved, with a period of roughly 6.9 years. The phase dispersion analysis gives a clear symmetric minimum for coherence time...
基于最小均方误差的圆弧分段曲线拟合方法%METHOD OF CIRCULAR ARC FRAGMENTED CURVE-FITTING BASED ON LEAST MEAN-SQUARE ERROR
Institute of Scientific and Technical Information of China (English)
涂嘉文; 徐守时; 谭勇
2001-01-01
We present a method of circular arc fragmented curve-fittingbased on least mean-square error rule in this paper. This method adopts self-adaptive gauss filter to process original curve smoothly to eliminate noise effects, and proposes a fragrmented algorithm that is adaptive to circular arc. Based on this algorithm, we use the circular arc as basic element to fit curve accroding to least mean-square error rule. The experiment results indicate that this method can eliminate noise effects as well as preserve the local characteristics of curve.%提出了一种基于最小均方误差准则的圆弧分段曲线拟合方法。该方法采用自适应高斯滤波器对原始曲线进行平滑处理以消除噪声影响，并提出了一种适合于圆弧曲线拟合的分段算法。在该算法的基础上根据最小均方误差准则，以圆弧作为基元对曲线进行拟合。实验结果表明，该方法能够较好地消除噪声影响并保留曲线的局部特征。
Energy Technology Data Exchange (ETDEWEB)
Hopwood, J.
1978-02-01
A microprocessor-based, stored-program controller which incorporates a floating-point arithmetic unit to perform complex mathematical computations was developed to determine the thickness of conductors on printed wiring boards. Conductor thickness is calculated from measured resistance by means of curve-fitting equations in the stored program. Called a film thickness calculator, the instrument demonstrates a method which may serve as a basis for other designs involving microprocessor-based data acquisition systems requiring low-speed calculations. 19 figures.
Huo, R.; Wehrens, H.R.M.J.; Buydens, L.M.C.
2004-01-01
The quality of DOSY NMR data can be improved by careful pre-processing techniques. Baseline drift, peak shift, and phase shift commonly exist in real-world DOSY NMR data. These phenomena seriously hinder the data analysis and should be removed as much as possible. In this paper, a series of preproce
DEFF Research Database (Denmark)
Baty, Florent; Ritz, Christian; van Gestel, Arnoldus
2016-01-01
regression. Simultaneous modeling of multiple kinetics requires nonlinear mixed models methodology. To the best of our knowledge, no such curve-fitting approach has been used to analyze multiple [Formula: see text]O2 kinetics in both research and clinical practice so far. METHODS: In the present study, we...... describe functionality of the R package medrc that extends the framework of the commonly used packages drc and nlme and allows fitting nonlinear mixed effects models for automated nonlinear regression modeling. The methodology was applied to a data set including 6MWT [Formula: see text]O2 kinetics from 61...... patients with chronic obstructive pulmonary disease (disease severity stage II to IV). The mixed effects approach was compared to a traditional curve-by-curve approach. RESULTS: A six-parameter nonlinear regression model was jointly fitted to the set of [Formula: see text]O2 kinetics. Significant...
DEFF Research Database (Denmark)
Baty, Florent; Ritz, Christian; van Gestel, Arnoldus;
2016-01-01
regression. Simultaneous modeling of multiple kinetics requires nonlinear mixed models methodology. To the best of our knowledge, no such curve-fitting approach has been used to analyze multiple [Formula: see text]O2 kinetics in both research and clinical practice so far. METHODS: In the present study, we...... describe functionality of the R package medrc that extends the framework of the commonly used packages drc and nlme and allows fitting nonlinear mixed effects models for automated nonlinear regression modeling. The methodology was applied to a data set including 6MWT [Formula: see text]O2 kinetics from 61...... patients with chronic obstructive pulmonary disease (disease severity stage II to IV). The mixed effects approach was compared to a traditional curve-by-curve approach. RESULTS: A six-parameter nonlinear regression model was jointly fitted to the set of [Formula: see text]O2 kinetics. Significant...
Slyusarenko, Kostyantyn; Abécassis, Benjamin; Davidson, Patrick; Constantin, Doru
2014-10-01
UV-Vis absorption spectroscopy is frequently used to characterize the size and shape of gold nanoparticles. We present a full-spectrum model that yields reliable results for the commonly encountered case of mixtures of spheres and rods in varying proportions. We determine the volume fractions of the two populations, the aspect ratio distribution of the nanorods (average value and variance) and the interface damping parameter. We validate the model by checking the fit results against small-angle X-ray scattering and transmission electron microscopy data and show that correctly accounting for the polydispersity in aspect ratio is essential for a quantitative description of the longitudinal plasmon peak.UV-Vis absorption spectroscopy is frequently used to characterize the size and shape of gold nanoparticles. We present a full-spectrum model that yields reliable results for the commonly encountered case of mixtures of spheres and rods in varying proportions. We determine the volume fractions of the two populations, the aspect ratio distribution of the nanorods (average value and variance) and the interface damping parameter. We validate the model by checking the fit results against small-angle X-ray scattering and transmission electron microscopy data and show that correctly accounting for the polydispersity in aspect ratio is essential for a quantitative description of the longitudinal plasmon peak. Electronic supplementary information (ESI) available: TEM images of nanoparticles and detailed analysis, simplified relations for the AS model, alternative estimate for the concentration and discussion of the dielectric constant chosen for bulk gold. See DOI: 10.1039/c4nr04155k
Institute of Scientific and Technical Information of China (English)
钱鹏; 沈为群; 刘旺开
2011-01-01
When applied in a high temperature environment simulation system, computer data acquisition fluctuates dramatically as the instability of the nonstandard thermocouple transmitter. A method which sending the thermocouple voltage to the computer directly is designed. Then a fitting function is acquired by curve fitting in poly-least-square, which could be used to avoid the waste of computer resource as the comparing table-searching work in program. And it could be seen that the fitting error is around ±3℃ in the high temperature area through error analysis. The fitting formula could be used in the signal acquisition of this kind of thermocouple. And the fitting degree could be adjusted according to the measurement precision.%针对在某高温环境模拟测控系统中,因变送器不稳定而导致温度采集值波动的问题,设计了一种直接将电热势信号采集到计算机的方法.为避免因计算机反复比较、查表而浪费资源,采用整体误差平方和多项式最小二乘法对热电势与温度值间的关系进行拟合.分析结果表明,在高温区城,拟合精度在士3℃左右.拟合公式可直接应用于此类热电偶信号采集中,并可根据精度要求适当调整拟合次数.
曲线拟合的广义最小一乘法%The Least Absolute Value Method of Curve Fitting
Institute of Scientific and Technical Information of China (English)
顾乐民
2011-01-01
In this paper, the formula solution of the Least Absolute Value method is introduced. The relationship between the formula solution and the Least Absolute Value's approximation are discussed.The realization of the best approximation that it is not only apply to linear functions also to nonlinear functions are explained.Two important characteristics of the data changes near the zero deviation point are put forward. A general Least Absolute Value method of human factors is established.Some examples of application for prediction are given.%介绍了最小一乘法的方程式解法；讨论了这种方程式解法与最小一乘逼近之间的关系；说明了它不仅适用于线性函数类也适用于非线性函数类的最佳逼近的实现；提出了零偏差点附近数据变化的两个重要特征；建立了一种具有“人为”因素的广义最小一乘法；并给出了该法在预测方面的几个应用实例.
Directory of Open Access Journals (Sweden)
Euzebio Medrado da Silva
2004-04-01
Full Text Available A distribuição granulométrica de partículas sólidas é essencial para as áreas de material de construção, mecânica dos solos, física dos solos, hidrossedimentologia, entre outras. As técnicas utilizadas na avaliação da distribuição granulométrica de amostras resultam em valores pontuais, dependendo de posterior interpolação para o traçado da curva granulométrica e a obtenção de diâmetros característicos específicos. A transformação de valores pontuais em funções contínuas pode ser realizada por meio de modelos matemáticos. Entretanto, há poucos estudos com a finalidade de determinar o melhor modelo para o ajuste de curvas granulométricas. O objetivo deste trabalho foi testar e comparar 14 diferentes modelos passíveis de utilização no traçado da curva granulométrica de partículas sólidas com base em quatro pontos medidos. O parâmetro de comparação entre os modelos foi a soma de quadrado dos erros entre os valores medidos e calculados. Os modelos mais recomendados no traçado da curva granulométrica, a partir de quatro pontos, são os de Skaggs et al. 3P, Lima & Silva 3P, Weibull 3P e Morgan et al. 3P, todos com três parâmetros de ajuste.Particle-size distribution is fundamental for characterizing construction materials, soil mechanics, soil physics, sediment-flux in rivers, and others. The techniques used to determine the particle-size distribution of a sample are point-wise, demanding posterior interpolation to fit the complete particle-size distribution curve and to obtain values of specific diameters. The transformation of discrete points into continuous functions can be made by mathematical models. However, there are few studies to determine the best model to fit particle-size distribution curves. The objective of this work was to test and compare 14 different models with feasibility to fit the cumulative particle-size distribution curve based on four measured points. The parameter used to compare
Correlation between ultrasonic nonlinearity and elastic nonlinearity in heat-treated aluminum alloy
Energy Technology Data Exchange (ETDEWEB)
Kim, Jong Beom; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of)
2017-04-15
The nonlinear ultrasonic technique is a potential nondestructive method to evaluate material degradation, in which the ultrasonic nonlinearity parameter is usually measured. The ultrasonic nonlinearity parameter is defined by the elastic nonlinearity coefficients of the nonlinear Hooke’s equation. Therefore, even though the ultrasonic nonlinearity parameter is not equal to the elastic nonlinearity parameter, they have a close relationship. However, there has been no experimental verification of the relationship between the ultrasonic and elastic nonlinearity parameters. In this study, the relationship is experimentally verified for a heat-treated aluminum alloy. Specimens of the aluminum alloy were heat-treated at 300°C for different periods of time (0, 1, 2, 5, 10, 20, and 50 h). The relative ultrasonic nonlinearity parameter of each specimen was then measured, and the elastic nonlinearity parameter was determined by fitting the stress-strain curve obtained from a tensile test to the 5th-order-polynomial nonlinear Hooke’s equation. The results showed that the variations in these parameters were in good agreement with each other.
矿井主要通风机性能曲线的最优多项式拟合%Optimal polynomial fitting for mine main fan characteristic curves
Institute of Scientific and Technical Information of China (English)
吴奉亮
2011-01-01
为确定主要通风机性能曲线多项式拟合函数的最优阶数,将回归系数的显著性作为最优阶数的判定依据.分析了基于最小二乘法的任意阶数主扇性能曲线拟合模型;指出了回归多项式的各项系数应与风压显著相关才是合理的,在合理基础之上阶数最大的即为最优;采用F检验法计算了回归多项式各系数的显著性.对于有m个样点的测定数据,通过m-1次拟合,可确定多项式的最优阶数.编制了相应的程序,实现了最佳阶数回归函数求解与曲线可视化,结合一包含13个测点的实例显示了这种方法的优越性.%For determinating the optimal power of polynomial fitting function of main fan' s characteristic curve, the significance of regression coefficient was taken as the criterion of optimum power. Based on the least square method, the fitting model of main fan' s characteristic curve with arbitrary power number was analyzed. The reasonable and optimal power of the regression functe were pointed out. F test was used to calculation significance of each coefficient. Where the count of sample data is n, fitting times of n - 1 was needed to calculate the optimum power. Program was coded to calculate the regression function and to visualize the curve. Finally, one example including thirteen group of sample datas was employed to display the advantage of this method.
基于BP网络的混凝土耗能器骨架曲线拟合%Based on BP Neural Network of Concrete Energy Dissipator Skeleton Curve Fitting
Institute of Scientific and Technical Information of China (English)
王文娟; 陈继光
2012-01-01
结合5种混凝土延性柱耗能器在低周期反复荷载作用下的试验数据研究,利用神经网络的工作原理,通过建立神经网络的输入层、隐含层、输出层,确定输入单元、输出单元和隐含层节点数,从而建立了BP神经网络的模型,并根据已有的部分试验数据数据.对网络进行训练,对各种混凝土延性柱耗能器骨架曲线进行了预测拟合,实现混凝土延性柱耗能器骨架曲线的数字化,使其成为具有分析和判断的拟合曲线功能,完整的描绘混凝土延性柱耗能器的骨架曲线,为后续混凝土延性柱耗能器性能研究的仿真模拟提供了可靠的数据模型.结果表明,这种方法是可行的.%Combined with 5 kinds of concrete ductility column energy dissipator at low cycle load test data research, the working principle of neural network, and by establishing a neural network's input layer, hidden and output layer, determine inputs unit, output unit and hidden node number, and to establish the BP neural network model, and part of the test data according to the existing data. Networks are trained to of all kinds of concrete ductility column energy dissipator skeleton curve fitting, forecast the realization concrete ductility column energy dissipator skeleton curve digital, make it become with analysis and judgment of the fitting curve function, complete description of concrete column energy dissipator ductility of skeleton curves, for the subsequent concrete ductility column energy dissipator performance simulation study provides the reliable data model. The results show that the method is feasible.
Institute of Scientific and Technical Information of China (English)
秦志伟; 李福金
2012-01-01
利用已完成的锦州市区基础控制成果对锦州市似大地水准面精化进行了研究。介绍了GPS高程的应用理论，大地水准高的计算方法以及利用曲面拟合法计算大地水准面高，并对结果进行了分析，绘制出高程异常等值线图。%The paper studies the quasi-geoid of Jinzhou through its finished basic control result. The paper introduces the application theory of GPS height and hoth the general method and the curved surface fitting method to measure geodetic height. At last,the paper analyzes the result,and the map ot geoid contour is drawn.
Institute of Scientific and Technical Information of China (English)
董闯; 宋松柏
2011-01-01
According to different curve fitting criterions, the calculation of swarm intelligence optimization algorithm to curve fitting in hydrologic frequency was studied, which can provide the basis for the hydraulic engineering planning and the water resources distributions. Taking the annual runoff data of 12 stations in north region of Shaanxi as an example, choosing 5 distribution types including 12 distributions,according to the regulations of design flood frequency computation for water resources and hydropower projects,applying OLS,ABS and WLS,taking MATLAB7.6 as the computing platfonn,applying the calculation of Simulated Annealing Algorithm,Genetic Algorithm,Particle Swarm Optimization and Ant Colony Algorithm to parameter estimation in hydrologic frequency. For different curve fitting criterions,all the best frequency distribution models of the annual runoff data in north region of Shaanxi are Generalized Logistic Distribution (GLO),the method of estimating parameters should select PSO. Comparing with other conventional optimization methods,swarm intelligence optimization algorithm does not dependent on target functions,it is a new way of inferring statistical parameters of annual runoff data frequency curve.%根据不同适线准则,研究群智能优化算法在水文频率曲线适线中的计算问题,为水利工程规划、水资源优化配置等提供依据.以陕北地区12个主要测站的年径流系列为例.选取五大分布类共12种分布线型,根据我国现行水利水电工程设计洪水计算规范,按照离(残)差平方和最小准则(OLS)、离(残)差绝对值和最小准则(ABS)、相对离差平方和最小准则(WLS),以MATLAB7.6为计算平台,研究模拟退火算法、遗传算法、粒子群算法和蚁群算法进行水文频率参数的估计.在不同适线准则下,陕北地区年径流最优频率分布模型为广义Logistic分布(Generalized Logistic Distribution,GLO),粒子群算法进行参数估算偏差最小.与传
Elasticity in Amorphous Solids: Nonlinear or Piecewise Linear?
Dubey, Awadhesh K; Procaccia, Itamar; Shor, Carmel A B Z; Singh, Murari
2016-02-26
Quasistatic strain-controlled measurements of stress versus strain curves in macroscopic amorphous solids result in a nonlinear-looking curve that ends up either in mechanical collapse or in a steady state with fluctuations around a mean stress that remains constant with increasing strain. It is therefore very tempting to fit a nonlinear expansion of the stress in powers of the strain. We argue here that at low temperatures the meaning of such an expansion needs to be reconsidered. We point out the enormous difference between quenched and annealed averages of the stress versus strain curves and propose that a useful description of the mechanical response is given by a stress (or strain) -dependent shear modulus for which a theoretical evaluation exists. The elastic response is piecewise linear rather than nonlinear.
Institute of Scientific and Technical Information of China (English)
柴胜丰; 唐健民; 杨雪; 谢伟玲; 韦霄; 蒋运生
2015-01-01
[Objective]In order to find the best photosynthesis light response curve model and obtain a more accurate photosynthetic parameters,the photosynthetic characteristics of Keteleeria calcarea was studied.[Methods]The photosynthesis light response curve was measured using the Li - 6400 portable photosynthesis system.4 light response curve models,including rectangular hyperbolic model, non-rectangular hyperbolic model,exponential model and modified rectangular hyperbolic mod-el,were applied to fitting its light response curve.[Results]According to calculated photo-synthetic parameters by 4 models,maximum net photosynthetic rate (Pnmax)estimated by rectan-gular hyperbola and non-rectangular hyperbola model were higher than that measured by exper-iment,while Pnmax fitted by exponential model and modified rectangular hyperbolic model were similar with that measured by experiment.Isat estimated by rectangular hyperbolic model,non-rectangular hyperbolic model and exponential model were far lower than the measured data,only Isat estimated by modified rectangular hyperbolic model was the closest to the measured data.The modified rectangular hyperbola model was the best model for fitting photosynthesis light response curve of Keteleeria calcarea.The Pnmax,Isat,Ic (compensation point)andRd(respiration rate)were 5.06μmol·m-2·s-1,850.45μmol·m-2·s-1,7.86μmol·m-2·s-1 and 0.816 μmol·m-2 ·s-1,respectively.[Conclusion]According to the relative errors of measured and fitted values of photosynthesis light response parameters,the sequence of fitting effect of the four light response models in descending order was modified rectangular hyperbola model > exponential model > non-rectangular hyperbola model >rectangular hyperbola model.%【目的】为找出黄枝油杉(Keteleeriacalcarea)光合光响应曲线的最佳模型，以得到较为准确的光合特征参数。【方法】采用 Li-6400便携式光合系统对黄枝油杉的光合光响应曲线进行测定，并通过4
Enlightening Volumes: Curve Fitting to Approximate Volumes
Buhl, David; O' Neal, Judy
2008-01-01
The current mantra in education is "technology, technology, technology." Many teachers and prospective teachers become frustrated with their lack of knowledge regarding the "appropriate" use of technology in the classroom. Prospective teachers need training in their education to understand how technology can be used "appropriately" in the…
Institute of Scientific and Technical Information of China (English)
冉雍
2016-01-01
重大工程建设一般会有定期的沉降和变形监测，本研究利用具有规律变化的Logistic和Gompertz曲线模型进行拟合，并以某大型发电厂为研究对象，利用近15年的监测数据，建立预测模型并进行精度评估。研究结果表明，若监测数据具有一定程度的稳定性，并对计算时监测数据进行合理取舍，对采取的全区、分区平均值或单一点高度值的检测数据，运用Logistic和Gompertz曲线模型来预测大型建筑物的沉降情况是可行的。%The major engineering construction regularly has the settlement and deformation monitoring, a regular variation of Logistic and Gompertz curve fitting model was used in this paper.Choosing a large power plant as the research object, the prediction model was established and the accuracy evaluated was conducted by using the monitoring data of recently 15 years.The research results showed that if the test data was stability in a certain degree, and the monitoring data was trade-off in reasonable, the Logistic and Gompertz curve model was feasible to predict the settlement of the large buildings condition by taking the entire district, partition or single point height value of the average detection data.
Indian Academy of Sciences (India)
S Venugopal Rao; P T Anusha; L Giribabu; Surya P Tewari
2010-11-01
We present our experimental results on the picosecond nonlinear optical (NLO) studies of symmetrical and unsymmetrical phthalocyanines, examined using the Z-scan technique. Both the open-aperture and closed-aperture Z-scan curves for three samples were recorded and the nonlinear coefficients were extracted from the theoretical fits. The nonlinear absorption/refraction contribution from the solvent was also identified. The observed open aperture behaviour for these molecules is understood in terms of the absorption coefficients of these molecules near 800 nm and the peak intensities used. It is established that these phthalocyanines exhibit large optical nonlinearities and, hence, are suitable for optical limiting applications.
Bayesian modeling growth curves for quail assuming skewness in errors
Directory of Open Access Journals (Sweden)
Robson Marcelo Rossi
2014-06-01
Full Text Available Bayesian modeling growth curves for quail assuming skewness in errors - To assume normal distributions in the data analysis is common in different areas of the knowledge. However we can make use of the other distributions that are capable to model the skewness parameter in the situations that is needed to model data with tails heavier than the normal. This article intend to present alternatives to the assumption of the normality in the errors, adding asymmetric distributions. A Bayesian approach is proposed to fit nonlinear models when the errors are not normal, thus, the distributions t, skew-normal and skew-t are adopted. The methodology is intended to apply to different growth curves to the quail body weights. It was found that the Gompertz model assuming skew-normal errors and skew-t errors, respectively for male and female, were the best fitted to the data.
Non-linear growth analysis of Sumatera thin tail sheep and its cross breds
Directory of Open Access Journals (Sweden)
Agus Suparyanto
2001-12-01
Full Text Available Growth curve is a figure of individual ability to express its genetic potential to maximum size under the existingenvironmental condition. Three non-linear growth curves, von Bertalanffy, Logistic and Gompertz, were used to analyze the weight-age relationship for five genotypes of sheep. The data were collected from IP2TP Sei Putih, North Sumatera. Num ber of animals which were collected consisted of five genotypes i.e, indigenous Sumatera (n=275, St. Croix (n=571, St. Croix Cross (n=899, Barbados Blackbelly Cross (n=471 and composite (n=740. The three non-linear growth curves were compared to obtain the most suitable curve for describing the shape of growth curves among sheep genotypes. The growth curves of von Bertalanffy fitted better than the others. The results showed that regression parameters of B or M (integral constante were significantly different (P0.05. The data show that there was correlation between A and k.
不同温度对钩栗光响应曲线拟合的影响%Effect of temperature on light response curve fitting of Castanopsis tibetana
Institute of Scientific and Technical Information of China (English)
张斌; 罗小浪
2016-01-01
Measuring and fitting the light response curve is one of the widely used methods when we cultivate the precious trees species. But as the difference among models and the genetic characters of tree species, the application of light response model is very important in the research of precious tree. The research were done in 2 years old seedlings of precious timber tree species of Castanopsis tibetana, using LI-6400 photosynthesis system to measure the photosynthesic characteristics of Castanopsis tibetana, compare 5 different light response models for the fitting of the characteristic data of the combination at 25℃ and 45℃ , the results show: high temperature stress can enhance the ability of using weak light, and also significantly reduced the maximum net photosynthetic capacity; under normal temperature (25 ℃ ) the value of modified rectangular hyperbolic model (MRHM) is higher by 12.99% - 30.57% compare to other models and measured value, while higher by 12.44% - 26.91% under higher temperature (45℃ ); compare all the models, under 25℃ , exponential model (EM), and modified exponential model (MEM) and non-rectangular hyperbolic model (NHM) have the best fitting effect, but under the condition of 45℃ , NHM and EM are the best models; Compere the real value and parameters of photosynthetic curve, NHM is the best model without the influence of temperature.%以珍贵用材树种钩栗2年生幼苗为研究对象，采用 LI-6400光合速率测试仪对钩栗成熟叶片的光合能力进行测定分析，在对钩栗25℃和45℃条件下的光合特征曲线进行拟合后发现5个模型间存在不同程度的差异。高温胁迫提高了钩栗对弱光的利用能力，也显著降低了钩栗的最大净光合能力；从模型的拟合效果来看，直角双曲线修正模型在常温时的模拟值与实际值和其他模型相比高出12.99%～30.57%，而在高温条件下却高出12.44%～26.91%，拟合效果最差；常温条件下指数模
The Gompertzian curve reveals fractal properties of tumor growth
Energy Technology Data Exchange (ETDEWEB)
Waliszewski, Przemyslaw; Konarski, Jerzy
2003-06-01
The normalized Gompertzian curve reflecting growth of experimental malignant tumors in time can be fitted by the power function y(t)=at{sup b} with the coefficient of nonlinear regression r{>=}0.95, in which the exponent b is a temporal fractal dimension, (i.e., a real number), and time t is a scalar. This curve is a fractal, (i.e., fractal dimension b exists, it changes along the time scale, the Gompertzian function is a contractable mapping of the Banach space R of the real numbers, holds the Banach theorem about the fix point, and its derivative is {<=}1). This denotes that not only space occupied by the interacting cancer cells, but also local, intrasystemic time, in which tumor growth occurs, possesses fractal structure. The value of the mean temporal fractal dimension decreases along the curve approaching eventually integer values; a fact consistent with our hypothesis that the fractal structure is lost during tumor progression.
A novel method for extracting acoustic nonlinearity parameters with diffraction corrections
Energy Technology Data Exchange (ETDEWEB)
Jeong, Hyunjo [Wonkwang University, Iksan (Korea, Republic of); Zhang, Shuzeng; Li, Xiongbing [Central South University, Changsha (China)
2016-02-15
A new method for determining the acoustic nonlinearity parameter using a nonlinear data fitting method is proposed. Based on the quasilinear theory of Westervelt's equation, the fundamental and second harmonic beam fields are expressed as a multi-Gaussian beam model that separates the attenuation and diffraction correction terms from the propagating plane waves. A nonlinear least squares curve fitting method is developed to extract the nonlinearity parameter without knowing the attenuation coefficients of the material being tested. The nonlinearity parameter of water is determined using the proposed method, and the result agrees well with the literature value. The attenuation coefficients of the fundamental and the second harmonic are also extracted and discussed.
Institute of Scientific and Technical Information of China (English)
孟红旗; 徐明岗; 吕家珑; 张会民; 蔡泽江
2013-01-01
以我国7个农田长期(15～29年)施肥试验的历史样品为供试土壤,研究了土壤质子化反应的动力学过程、土壤性质(pH值和SOM)和施肥措施对土壤酸中和能力(ANC)的影响.根据土壤酸滴定曲线,采用二次曲线方程拟合,pH=3.5为参考值,图解法求解土壤ANC.结果表明,土壤质子化过程可视作由质子扩散控制的假二级反应动力学过程:在酸添加后的100 h内,土壤ANC与反应时间的对数值近似线性相关；机械振荡和提高温度可加快土壤质子化反应的进程.土壤ANC在指示土壤酸碱程度上较pH灵敏,但对SOM的变化较土壤酸缓冲容量(ABC)不敏感；土壤ANC受长期施肥措施(施无机氮组＜不施氮肥组≈有机无机氮配施组)的显著影响,影响的程度因各试验点而异.对土壤酸中和能力的研究加深了对农田土壤酸缓冲机制的认识.%To better understand the mechanism of acid-buffering in croplands we evaluated their acid-neutralizing capacity (ANC) of topsoil using quadratic curve fitting. The kinetics of soil protonation reaction and impacts of soil properties(pH and SOM, soil organic matter) and fertilizations on soil ANC were studied from seven historical soils under 15~29 years long-term fertilizations in China. According to the acid titration curve fitted by the quadratic equation, soil ANC was generated by a graphic method at the reference of pH=3.5. The process of soil protonation was considered as the pseudo second—order reaction kinetics controlled by the proton diffusion in soil particles. An approximate linear correlation between ANC and the logarithmic value of reaction time was found less than 100 hours after acid addition. Soil protonation reaction was accelerated by mechanical shaking or increase of temperature. Based on the analysis of correlation and comparison in different experimental sites, soil ANC was more sensitive to soil acid—base status rather than pH, but less sensitive to SOM
Institute of Scientific and Technical Information of China (English)
吴珊丹
2016-01-01
with the development of computer technology and Internet technology,automation technology,computer technolo⁃gy and network technology has been widely used in various aspects of the current life and work. In the process of social develop⁃ment,different types and structural products need to be produced to meet the different requirements of users. In order to reduce the production cost of the products,and improve the competitiveness of the market,design of the product manufacturing technol⁃ogy and optimization of the products should be strengthened in product design,manufacture and management. The graphic image vector quantization is a fast digital processing method,which can improve the quality of the product design,optimize the prod⁃uct design,effectively reduce the production cost,and improve market competitiveness. The analytical investigation for spline curve fitting,image digital vector quantization in computer aided technology,and the related contents is carried out in this pa⁃per.%在社会发展的过程中，需要生产不同类型、不同结构等的产品以满足用户的不同需求。为了降低产品的生产成本，并提高市场的竞争力，需要从产品的设计、制造、管理等方面入手，加强产品的设计，优化产品生产制造技术等。结果表明，应用图形图像数字数量化分析，可以提高产品设计的质量，优化设计，有效地降低生产成本，提高市场竞争力。
Institute of Scientific and Technical Information of China (English)
黄玲; 杨鹏辉; 谢文; 吴春艳
2016-01-01
本文主要研究太阳影子定位技术，以太阳高度角为切入点，借助天文三角形知识，探究太阳高度角、太阳方位角、太阳时角、太阳赤纬与经纬度、日期、地方时的关系，结合曲线拟合、联立方程式的方法，建立太阳影子定位的优化模型，运用MATLAB、EXCEL软件研究出太阳影子的变化规律、基于影子顶点坐标条件下物体的定时、定位，并将研究结果推广到视频数据分析领域对视频进行定位、定时。%The thesis majors in the positioning of sunˊs shadow,in our study,solar height angle is breakthrough,by means of the knowledge of the astronomical triangle,we analysed the quantitative relationship between sun elevation angle,solar azi-muth,solar hour,solar declination angle and longitude,latitude,date,local time. Combining with the method of curve fitting and simultaneous equations,we set up the sun’s shadow positioning optimizing model. By using MATLAB and EXCEL soft-ware,we worked out the laws for the change of sun’s shadow,and ascertained the location and date. Finally we promoted our research result to the field of video data analysis.
葡萄光合作用光响应曲线拟合模型比较研究%Comparison of Light-response Curve Fitted Models for Grape
Institute of Scientific and Technical Information of China (English)
白云岗; 刘洪波; 张江辉; 冯杰; 丁平
2016-01-01
The optimal model with the most closeness between measured and simulated value was selected.In order to find the best photo-response model of grape leaf in Turpan area,the photosynthetic response curve of grape leaf was fitted by quadratic polynomi-al,rectangular hyperbolic,exponential,rectangular hyperbolic,non-rectangular hyperbolic and modified rectangular hyperbolic mod-el.Showed that the exponential and rectangular hyperbolic model could not explain the photosynthetic suppress phenomenon of light saturation region.To some extent,the quadratic polynomial model displayed photosynthetic suppress phenomenon,but it had a very large difference between simulated photosynthetic parameters and measured ones,which defied common sense.The non-rectangular hyperbolic model explained the photosynthetic suppress phenomenon,but the fitted maximum net photosynthetic rate was higher than the measured values.The modified rectangular hyperbolic model with the most closeness between simulated value photosynthet-ic parameters and measured ones could best reflect the photosynthetic response curve for grape leaf under different light intensities, especially at the light saturation region.Whose fitted net photosynthetic rate (Amax),light saturation point (LSP),light compensa-tion point (LCP),dark respiration rate (Rday)and the initial quantum efficiency (α)was 10.627,1 178.362,67.487,2.943μmol/(m2 ·s)and 0.05.The modified rectangular hyperbolic model is suit to simulate the photosynthetic response curve for grape leaf un-der different light intensities at Turpan area.%通过分析各模型求取的光合参数模拟值与实测值的接近程度，探讨了各模型在葡萄光响应曲线研究中的适用性。为了筛选适合吐鲁番地区的葡萄光响应模型，采用二次多项式模型、指数函数模型、直角双曲线模型、非直角双曲线模型和修正的直角双曲线模型对葡萄光合作用的光响应曲线进行拟合，表明：指数函数模型
Energy Technology Data Exchange (ETDEWEB)
Hernandez Rodriguez, J.; Martin Rincon, C.; Garcia Repiso, S.; Ramos Paheo, J. A.; Verde Velasco, J. M.; Sena Espinel, E. de
2013-07-01
The non-linear relationship between dose and the optical density, characteristic plates radiochromic Gafchromic EBT and EBT2, has been studied by various authors, whose publications are proposed different functional forms that fit the specific values measured curves that allow the full range of useful dose calibration. The objective of the work focuses on evaluating the influence of the use of different calibration curves in the dose measurement for quality control of IMRT treatments. (Author)
Directory of Open Access Journals (Sweden)
Fernanda Gomes da Silveira
2011-04-01
Full Text Available Este estudo teve como objetivo utilizar a análise de agrupamento para classificar modelos de regressão não-lineares usados para descrever a curva de crescimento de ovinos cruzados, tendo em vista os resultados de diferentes avaliadores de qualidade de ajuste. Para tanto, utilizaram-se dados de peso-idade dos seguintes cruzamentos entre raças de ovinos de corte: Dorper x Morada Nova, Dorper x Rabo Largo e Dorper x Santa Inês. Após a indicação do melhor modelo, objetivou-se ainda aplicar a técnica de identidade de modelos a fim de identificar o cruzamento mais produtivo. Foram ajustados doze modelos não-lineares, cuja qualidade de ajuste foi medida pelo coeficiente de determinação ajustado, critérios de informação de Akaike e Bayesiano, erro quadrático médio de predição e coeficiente de determinação de predição. A análise de agrupamento indicou o modelo Richards como o mais adequado para descrever as curvas de crescimento dos três grupos genéticos considerados, e os testes de identidade de modelos indicaram o cruzamento Dorper x Santa Inês como sendo o mais indicado para a pecuária local.This study had the objectives to use the cluster analysis in order to classify nonlinear regression models used to describe the growth curve in relation to different quality fit evaluators. Were utilized weight-age data from the following crossbred beef lambs Dorper x Morada Nova, Dorper x Rabo Largo e Dorper x Santa Inês. After the choice of the best model, we aimed also to apply the model identity in order to identify the most efficient crossbred group. Eleven nonlinear models were used, whose fit quality was measured by determination coefficient, Akaike information criterion, Bayesian information criterion, mean quadratic error of prediction and predicted determination coefficient. The cluster analysis indicated the Richards as the best model for the three data sets, and the model identity tests revealed that the Dorper x Santa In
Institute of Scientific and Technical Information of China (English)
薛明富; 胡爱群
2011-01-01
虽然非线性助听器选配算法相继被提出,但对各选配算法的研究并不充分.对常用的NAL-NL1和DSL[i/o]5.0等选配算法进行了研究与仿真.首先研究了各选配算法的设计原则,并仿真分析了在各种典型听力图下,各算法所给出的声学响应特性(增益、拐点、压缩比、各频段的强调程度等),计算了客观的评价指标(响度、语音清晰度等).实验证实,NAL-NL1的原则是对语言的所有频率带整体进行响度均衡化,并且最大化语言清晰度,NAL系列算法均与此类似,而DSL[i/o]5.0的原则是响度正常化.对同样的听力图,由于设计原则与理念的不同,各算法给出了不同的响应特性,在响度和语音清晰度上也有所差异,讨论了设计原则对响应特性的影响及其对应关系.还对非线性助听器选配算法的研究现状和未来发展方向进行了一定的探讨.%Various fitting methods for non-linear hearing aids have been proposed. But the study of these fitting methods is not sufficient, and no such work has been done in China. This paper gives the study and the simulation of common fitting methods for non-linear hearing aids, such as NAL-NL1 and DSL[I/o]5.0. First, it studies the design principles of these fitting methods. Then, it simulates and analysis the acoustic response characteristics of fitting methods under various typical audiograms, such as gain, knee points, compression ratio and the degree of emphasis in different frequency bands. It calculates the objective assessment indexes like loudness and speech intelligibility. Experiments have confirmed that the principle of NAL-NL1 is to get loudness equalization among all frequency bands, and maximize the speech intelligibility. NAL series of fitting methods are similar to this while the DSL[I/o]5.0 focuses on loudness normalization. Under the same audiogram, they give different acoustic response characteristics due to the differences of design principles and
[Dose response curve of paclitaxel measured by histoculture drug response assay].
Yoshimasu, Tatsuya; Oura, Shoji; Hirai, Issei; Kokawa, Yozo; Okamura, Yoshitaka; Furukawa, Tomoko
2005-04-01
Dose response curves of paclitaxel were measured by histoculture drug response assay (HDRA) in 11 lung cancer patients. Inhibition rates of paclitaxel at several concentrations were measured and fitted to the sigmoid dose response curve, using non-linear least square analysis, with fitting equation y=A (1-1/(1+exp (b (x-log (ED50)). Parameters A, b, and ED50 were 88.3+/-6.0 (80.0-100.0) %, 9.57+/-4.32 (2.25-15.0), and 26.8+/-8.1 (15.0-41.0) microg/ml, respectively. The parameter b was lower in well-differentiated tumors compared with moderately and poorly-differentiated tumors. Dose response curves of paclitaxel could be measured by HDRA in lung cancer. This method provides us more information for drug sensitivity than the usual HDRA method. This may lead to the improved accuracy of HDRA.
Extensive fitness and human cooperation.
van Hateren, J H
2015-12-01
Evolution depends on the fitness of organisms, the expected rate of reproducing. Directly getting offspring is the most basic form of fitness, but fitness can also be increased indirectly by helping genetically related individuals (such as kin) to increase their fitness. The combined effect is known as inclusive fitness. Here it is argued that a further elaboration of fitness has evolved, particularly in humans. It is called extensive fitness and it incorporates producing organisms that are merely similar in phenotype. The evolvability of this mechanism is illustrated by computations on a simple model combining heredity and behaviour. Phenotypes are driven into the direction of high fitness through a mechanism that involves an internal estimate of fitness, implicitly made within the organism itself. This mechanism has recently been conjectured to be responsible for producing agency and goals. In the model, inclusive and extensive fitness are both implemented by letting fitness increase nonlinearly with the size of subpopulations of similar heredity (for the indirect part of inclusive fitness) and of similar phenotype (for the phenotypic part of extensive fitness). Populations implementing extensive fitness outcompete populations implementing mere inclusive fitness. This occurs because groups with similar phenotype tend to be larger than groups with similar heredity, and fitness increases more when groups are larger. Extensive fitness has two components, a direct component where individuals compete in inducing others to become like them and an indirect component where individuals cooperate and help others who are already similar to them.
Identification of Nonlinearities in Joints of a Wing Structure
Directory of Open Access Journals (Sweden)
Sani M.S.M.
2016-01-01
Full Text Available Nonlinear structural identification is essential in engineering. As new materials are being used andstructures become slender and lighter, nonlinear behaviour of structures becomes more important. There have been many studies into the development and application of system identification methods for structural nonlinearity based on changes in natural frequencies, mode shapes and damping ratios. A great challenge is to identify nonlinearity in large structural systems. Much work has been undertaken in the development of nonlinear system identification methods (e.g. Hilbert Transform, NARMAX, and Proper Orthogonal Decomposition, however, it is arguable that most of these methods are cumbersome when applied to realistic large structures that contain mostly linear modes with some local nonlinearity (e.g. aircraft engine pylon attachment to a wing. In this paper, a multi-shaker force appropriation method is developed to determine the underlying linear and nonlinear structural properties through the use of the measurement and generation of restoring force surfaces. One undamped mode is excited in each multi-shaker test. Essentially, this technique is a derivative of the restoring surface method and involves a non-linear curve fitting performed in modal space. A reduced finite element model is established and its effectiveness in revealing the nonlinear characteristics of the system is discussed. The method is demonstrated through both numerical simulations and experiments on a simple jointed laboratory structure with seeded faults, which represents an engine pylon structure that consists of a rectangular wing with two stores suspended underneath.
On the analysis of Canadian Holstein dairy cow lactation curves using standard growth functions.
López, S; France, J; Odongo, N E; McBride, R A; Kebreab, E; AlZahal, O; McBride, B W; Dijkstra, J
2015-04-01
Six classical growth functions (monomolecular, Schumacher, Gompertz, logistic, Richards, and Morgan) were fitted to individual and average (by parity) cumulative milk production curves of Canadian Holstein dairy cows. The data analyzed consisted of approximately 91,000 daily milk yield records corresponding to 122 first, 99 second, and 92 third parity individual lactation curves. The functions were fitted using nonlinear regression procedures, and their performance was assessed using goodness-of-fit statistics (coefficient of determination, residual mean squares, Akaike information criterion, and the correlation and concordance coefficients between observed and adjusted milk yields at several days in milk). Overall, all the growth functions evaluated showed an acceptable fit to the cumulative milk production curves, with the Richards equation ranking first (smallest Akaike information criterion) followed by the Morgan equation. Differences among the functions in their goodness-of-fit were enlarged when fitted to average curves by parity, where the sigmoidal functions with a variable point of inflection (Richards and Morgan) outperformed the other 4 equations. All the functions provided satisfactory predictions of milk yield (calculated from the first derivative of the functions) at different lactation stages, from early to late lactation. The Richards and Morgan equations provided the most accurate estimates of peak yield and total milk production per 305-d lactation, whereas the least accurate estimates were obtained with the logistic equation. In conclusion, classical growth functions (especially sigmoidal functions with a variable point of inflection) proved to be feasible alternatives to fit cumulative milk production curves of dairy cows, resulting in suitable statistical performance and accurate estimates of lactation traits. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
The mathematical description of lactation curves in dairy cattle
Directory of Open Access Journals (Sweden)
Giuseppe Pulina
2011-10-01
Full Text Available This review gives an overview of the mathematical modelling of lactation curves in dairy cattle. Over the last ninety years, the development of this field of study has followed the main requirements of the dairy cattle industry. Non-linear parametric functions have represented the preferred tools for modelling average curves of homogeneous groups of animals, with the main aim of predicting yields for management purposes. The increased availability of records per individual lactations and the genetic evaluation based on test day records has shifted the interest of modellers towards more flexible and general linear functions, as polynomials or splines. Thus the main interest of modelling is no longer the reconstruction of the general pattern of the phenomenon but the fitting of individual deviations from an average curve. Other specific approaches based on the modelling of the correlation structure of test day records within lactation, such as mixed linear models or principal component analysis, have been used to test the statistical significance of fixed effects in dairy experiments or to create new variables expressing main lactation curve traits. The adequacy of a model is not an absolute requisite, because it has to be assessed according to the specific purpose it is used for. Occurrence of extended lactations and of new productive and functional traits to be described and the increase of records coming from automatic milking systems likely will represent some of the future challenges for the mathematical modelling of the lactation curve in dairy cattle.
Fitness club
2011-01-01
General fitness Classes Enrolments are open for general fitness classes at CERN taking place on Monday, Wednesday, and Friday lunchtimes in the Pump Hall (building 216). There are shower facilities for both men and women. It is possible to pay for 1, 2 or 3 classes per week for a minimum of 1 month and up to 6 months. Check out our rates and enrol at: http://cern.ch/club-fitness Hope to see you among us! CERN Fitness Club fitness.club@cern.ch
Institute of Scientific and Technical Information of China (English)
陈勇; 杨雪; 刘焕淋; 杨凯; 张玉兰
2016-01-01
detecting algorithm is the key technology of the system demodu-lation.The current peak detecting algorithms has a precondition for peak detection on FBG reflective spectrum,that the FBG reflective spectrum was a standard Gaussian model.But FBG reflective spectrum is not a standard Gaussian spectrum owing to the practical manufacture process and the individual environment;actually,it is an asymmetrical Gaussian spectrum.The experi-ment would achieve a lower accuracy because of this asymmetric property during peak-seeking.Based on the defect of the exist-ing algorithm,an Exponent Modified Gaussian (EMG)Curve Fitting peak detecting algorithm is proposed in this paper.In the proposed algorithm,the coarse location was first determined by three times j udgments and it can remove the false peak and peak invalid at the same time.Based on this,as the center of the coarse localization point to reconstruct the spectrum,and using the integral to j udge the peak bias;then according to different peak bias,it revised the peak by the prepared exponential modified function.Simulation results show that at normal temperature or under variable temperature conditions,by comparing with direct peak searching algorithm,Gaussian fitting algorithm and the algorithm proposed by literature,the error of EMG peak detection algorithm is the minimum and high peak detecting precision.The algorithm proposed in this paper considers the FBG reflection spectrum characteristic of asymmetric effect.From its spectrum character,the EMG algorithm solves the problem of the limits of traditional peak detecting algorithm,meanwhile also guarantees a high-precision peak search results.
Fitness Club
2011-01-01
The CERN Fitness Club is organising Zumba Classes on the first Wednesday of each month, starting 7 September (19.00 – 20.00). What is Zumba®? It’s an exhilarating, effective, easy-to-follow, Latin-inspired, calorie-burning dance fitness-party™ that’s moving millions of people toward joy and health. Above all it’s great fun and an excellent work out. Price: 22 CHF/person Sign-up via the following form: https://espace.cern.ch/club-fitness/Lists/Zumba%20Subscription/NewForm.aspx For more info: fitness.club@cern.ch
Interface-wave dispersion curves inversion based on nonlinear Bayesian theory%根据非线性贝叶斯理论的界面波频散曲线反演
Institute of Scientific and Technical Information of China (English)
李翠琳; Stan E Dosso; Hefeng Dong
2012-01-01
通过时频分析法从海底环境噪声数据中提取界面波频散曲线,进而采用非线性贝叶斯反演方法估算海底沉积物厚度、剪切波速度、压缩波速度和密度等参数及其不确定性.参数的最大后验概率(MAP)估计值和边缘概率分布分别通过自适应单纯形模拟退火法和Metropolis-Hastings采样法在各参数先验区间内搜索获得,采用贝叶斯信息准则(BIC)从不同参数化模型中选择最优模型.界面波频散曲线反演结果表明:满足实测数据的最优海底模型结构为3层均匀分布剪切波速度剖面结构,海底深度的反演精度在800 m以内,比起压缩波速度和密度,剪切波速度的不确定性更小,对界面波频散曲线更敏感.%This paper applies a dataset of ocean ambient noise data to extract interface-wave dispersion curves using time-frequency analysis. The nonlinear Bayesian inversion is applied to estimate seabed sediment parameters such as thickness, shear-wave velocity, compression wave velocity and density, and their uncertainties from interface-wave dispersion curves. The maximum a posterior (MAP) model and marginal probability distributions of parameters are estimated using posterior probability densities computed by adaptive simplex simulated annealing and Metropolis-Hastings sampling methods. The Bayesian information criterion is applied to determine the optimal model that fully explains the observed data by the different parameterizations. The inversion results indicate that 3-uniform-layer model is chosen as the preferred parameterization. The resolution of inversion is up to 800 m-depth. The shear-wave velocity and layer thickness have fewer uncertainties and are more sensitive to the interface wave dispersion than the compression wave velocity and density.
Directory of Open Access Journals (Sweden)
Leonardo Machado Pires
2007-10-01
Full Text Available Os modelos polinomiais são mais difundidos no meio florestal brasileiro na descrição do perfil de árvores devido à sua facilidade de ajuste e precisão. O mesmo não ocorre com os modelos não-lineares, os quais possuem maior dificuldade de ajuste. Dentre os modelos não-lineares clássicos, na descrição do perfil, podem-se citar o de Gompertz, o Logístico e o de Weibull. Portanto, este estudo visou comparar os modelos lineares e não lineares para a descrição do perfil de árvores. As medidas de comparação foram o coeficiente de determinação (R², o erro-padrão residual (s yx, o coeficiente de determinação corrigido (R²ajustado, o gráfico dos resíduos e a facilidade de ajuste. Os resultados ressaltaram que, dentre os modelos não-lineares, o que obteve melhor desempenho, de forma geral, foi o modelo Logístico, apesar de o modelo de Gompertz ser melhor em termos de erro-padrão residual. Nos modelos lineares, o polinômio proposto por Pires & Calegario foi superior aos demais. Ao comparar os modelos não-lineares com os lineares, o modelo Logístico foi melhor em razão, principalmente, do fato de o comportamento dos dados ser não-linear, à baixa correlação entre os parâmetros e à fácil interpretação deles, facilitando a convergência e o ajuste.Polynomial models are most commonly used in Brazilian forestry for taper modeling due to its straightforwardly fitting and precision. The use of nonlinear regression classic models, like Gompertz, Logistic and Weibull, is not very common in Brazil. Therefore, this study aimed to verify the best nonlinear and linear models, and among these the best model to describe the longitudinal tree profile. The comparison measures were: R², syx, R²adjusted, residual graphics and fitting convergence. The results pointed out that among the non-linear models the best behavior, in general, was given by the Logistic model, although the Gompertz model was superior compared with the Weibull
On the nonlinear anelastic behaviour of AHSS
Torkabadi, A.; Meinders, V. T.; van den Boogaard, A. H.
2016-08-01
It has been widely observed that below the yield stress the loading/unloading stress-strain curves of plastically deformed metals are in fact not linear but slightly curved, showing a hysteresis behaviour during unloading/reloading cycles. In addition to the purely elastic strain, extra dislocation based micro-mechanisms are contributing to the reversible strain of the material which results in the nonlinear unloading/reloading behaviour. This extra reversible strain is the so called anelastic strain. As a result, the springback will be larger than that predicted by FEM considering only the recovery of the elastic strain. In this work the physics behind the anelastic behaviour is discussed and experimental results for a dual phase steel are demonstrated. Based on the physics of the phenomenon a model for anelastic behaviour is presented that can fit the experimental results with a good accuracy.
Directory of Open Access Journals (Sweden)
Kleber Régis Santoro
2005-12-01
Full Text Available Objetivou-se estimar parâmetros genéticos e fenotípicos de curvas de crescimento de modelos não-lineares. Foram analisados dados de pesagem constantes no banco de dados de Controle de Desenvolvimento Ponderal da Associação Brasileira de Criadores de Zebu (ABCZ, referentes a 24.028 animais Zebu, nascidos entre 1960 e 2000, das raças Guzerá, Nelore e Nelore Mocho. As pesagens ocorreram ao nascimento e em intervalos de 90 dias até dois anos de idade. Os seguintes modelos não-lineares foram utilizados na análise dos dados de peso-idade: Brody, Gompertz, Logístico, von Bertalanffy e Richards. Os efeitos fixos estudados no modelo misto foram sexo, rebanho, ano e mês de nascimento e regime de criação. As herdabilidades para os parâmetros foram de baixa a alta magnitude, em geral, para todos os modelos. As correlações genéticas entre peso assintótico e taxa de maturidade e entre peso assintótico e velocidade de crescimento foram negativas, enquanto aquelas entre taxa de maturidade e velocidade de crescimento foram positivas. As correlações fenotípicas foram negativas entre peso assintótico e taxa de crescimento e entre peso assintótico e velocidade de crescimento e positivas entre taxa e velocidade de crescimento. Encontrou-se variabilidade possível de ser explorada em um programa de melhoramento genético, especialmente para a raça Nelore, que apresentou amostra de dados e resultados mais consistentes.Weight records of 24.028 zebu animals from Guzerá, Nelore, and Polled Nelore breeds available from Brazilian Association of Zebu Breeders (ABCZ database were used to estimate heritabilities of growth curve parameters. Non-linear Brody, Gompertz, Logistic, Mitscherlich, von Bertalanffy, Richards, and Double Logistic models including sex, farm, year of birth, month of birth, raising system, and interaction sex*raising system as fixed effects and sire and dam, as random effects were adjusted using weight-age records of animals
原状黄土土水特征曲线拟合方法研究%Study on soil-water characteristics curve fitting for undisturbed loess soil
Institute of Scientific and Technical Information of China (English)
郭鸿; 陈茜; 陈栋梁; 李军
2016-01-01
In order to explore the fitting approach for SWCC of undisturbed loess, the SWCC of loess soil samples in Baoji, Qishan and Yangling were fitted through 5 conventional fitting methods, and also results of indoor dehumidification experiment of matric suction pressure plate were compared with the fitting data. The results show that Fredlund & Xing, van Genuchten and Brooks&Corey fitting methods can better reflect undisturbed loess SWCC, while van Genuchten&Burdine ( VGB) and van Ge-nuchten &Mualem ( VBM) are not suitable for describing undistributed loess SWCC as their residual moisture contents are differ-ent from practical condition. Finally, a simple and practical engineering SWCC prediction formula was proposed and verified by tests.%为了探索原状黄土土水特征曲线的拟合方法,采用已有的经典拟合方法对宝鸡、岐山和杨凌3个地区的原状黄土的土水特征曲线( SWCC)进行了拟合,并和室内基质吸力压力板减湿试验结果进行了对比。结果表明,Fredlund & Xing,Van Genuchten和Brooks & Corey三种拟合方法都可以较好地反映原状黄土的SWCC,而van Genuchten & Burdine 和van Genuchten & Mualem两种方法由于残余含水率和实际差别过大,并不适合描述原状黄土的SWCC。最后建议了一种简单而又适合实际工程采用的SWCC拟合公式,并通过试验验证了其可行性。
Piecewise compensation for the nonlinear error of fiber-optic gyroscope scale factor
Zhang, Yonggang; Wu, Xunfeng; Yuan, Shun; Wu, Lei
2013-08-01
Fiber-Optic Gyroscope (FOG) scale factor nonlinear error will result in errors in Strapdown Inertial Navigation System (SINS). In order to reduce nonlinear error of FOG scale factor in SINS, a compensation method is proposed in this paper based on curve piecewise fitting of FOG output. Firstly, reasons which can result in FOG scale factor error are introduced and the definition of nonlinear degree is provided. Then we introduce the method to divide the output range of FOG into several small pieces, and curve fitting is performed in each output range of FOG to obtain scale factor parameter. Different scale factor parameters of FOG are used in different pieces to improve FOG output precision. These parameters are identified by using three-axis turntable, and nonlinear error of FOG scale factor can be reduced. Finally, three-axis swing experiment of SINS verifies that the proposed method can reduce attitude output errors of SINS by compensating the nonlinear error of FOG scale factor and improve the precision of navigation. The results of experiments also demonstrate that the compensation scheme is easy to implement. It can effectively compensate the nonlinear error of FOG scale factor with slightly increased computation complexity. This method can be used in inertial technology based on FOG to improve precision.
Institute of Scientific and Technical Information of China (English)
赵亚萍; 咸春颖; 余逸男
2013-01-01
为了避免大量数据处理、手工作图外推方法带来的误差,利用Origin8.0软件采用改进的非线性拟合方法对电导法测定乙酸乙酯皂化反应的实验数据进行了处理,在未知反应级数的前提下,分析并比较了多项式模型与指数衰减模型的拟合结果.研究表明,采用三次指数衰减模型能够达到较优的拟合效果,与其他现有数据处理方法相比,其获得的反应速率常数结果相对误差也较小.该方法不需要测定反应的初始电导,方便、快捷地完成了反应级数的确定,反应速率常数的测定以及反应活化能的求算,在拓展学生计算机软件应用能力的同时提高了分析结果的准确度.%To avoid the errors caused by the processing of a great number of data and hand drawing, an improved nonlinear fitting method is applied to process the dynamics experimental data of acetic ether saponification with Origin 8.0, and the fitting results of polynomial model and exponential degression model are analyzed and compared. The results show that the three order exponential degression model gives the good fitting effect with unknown reaction order, in which the relative error of the reaction rate constant obtained is smaller, compared with other data processing methods. It is unnecessary to measure the initial conductance value and the reaction order, yet, the reaction rate coefficient and activation energy can be determined quickly and easily. The ability of students in computer software applications is expanded and the accuracy of the analysis results is improved.
Nonlinear calculating method of pile settlement
Institute of Scientific and Technical Information of China (English)
贺炜; 王桂尧; 王泓华
2008-01-01
To study calculating method of settlement on top of extra-long large-diameter pile, the relevant research results were summarized. The hyperbola model, a nonlinear load transfer function, was introduced to establish the basic differential equation with load transfer method. Assumed that the displacement of pile shaft was the high order power series of buried depth, through merging the same orthometric items and arranging the relevant coefficients, the solution which could take the nonlinear pile-soil interaction and stratum properties of soil into account was solved by power series. On the basis of the solution, by determining the load transfer depth with criterion of settlement on pile tip, the method by making boundary conditions compatible was advised to solve the load-settlement curve of pile. The relevant flow chart and mathematic expressions of boundary conditions were also listed. Lastly, the load transfer methods based on both two-broken-line model and hyperbola model were applied to analyzing a real project. The related coefficients of fitting curves by hyperbola were not less than 0.96, which shows that the hyperbola model is truthfulness, and is propitious to avoid personal error. The calculating value of load-settlement curve agrees well with the measured one, which indicates that it can be applied in engineering practice and making the theory that limits the design bearing capacity by settlement on pile top comes true.
Fitness Club
2012-01-01
Open to All: http://cern.ch/club-fitness fitness.club@cern.ch Boxing Your supervisor makes your life too tough ! You really need to release the pressure you've been building up ! Come and join the fit-boxers. We train three times a week in Bd 216, classes for beginners and advanced available. Visit our website cern.ch/Boxing General Fitness Escape from your desk with our general fitness classes, to strengthen your heart, muscles and bones, improve you stamina, balance and flexibility, achieve new goals, be more productive and experience a sense of well-being, every Monday, Wednesday and Friday lunchtime, Tuesday mornings before work and Thursday evenings after work – join us for one of our monthly fitness workshops. Nordic Walking Enjoy the great outdoors; Nordic Walking is a great way to get your whole body moving and to significantly improve the condition of your muscles, heart and lungs. It will boost your energy levels no end. Pilates A body-conditioning technique de...
Energy Technology Data Exchange (ETDEWEB)
Christensen, S. W.; Goodyear, C. P.; Kirk, B. L.
1982-03-01
This report addresses the validity of the utilities' use of the Ricker stock-recruitment model to extrapolate the combined entrainment-impingement losses of young fish to reductions in the equilibrium population size of adult fish. In our testimony, a methodology was developed and applied to address a single fundamental question: if the Ricker model really did apply to the Hudson River striped bass population, could the utilities' estimates, based on curve-fitting, of the parameter alpha (which controls the impact) be considered reliable. In addition, an analysis is included of the efficacy of an alternative means of estimating alpha, termed the technique of prior estimation of beta (used by the utilities in a report prepared for regulatory hearings on the Cornwall Pumped Storage Project). This validation methodology should also be useful in evaluating inferences drawn in the literature from fits of stock-recruitment models to data obtained from other fish stocks.
DEFF Research Database (Denmark)
Nielsen, Karen L.; Pedersen, Thomas M.; Udekwu, Klas I.
2012-01-01
of each isolate was determined in a growth competition assay with a reference isolate. Significant fitness costs of 215 were determined for the MRSA isolates studied. There was a significant negative correlation between number of antibiotic resistances and relative fitness. Multiple regression analysis...... to that seen in Denmark. We propose a significant fitness cost of resistance as the main bacteriological explanation for the disappearance of the multiresistant complex 83A MRSA in Denmark following a reduction in antibiotic usage.......Denmark and several other countries experienced the first epidemic of methicillin-resistant Staphylococcus aureus (MRSA) during the period 196575, which was caused by multiresistant isolates of phage complex 83A. In Denmark these MRSA isolates disappeared almost completely, being replaced by other...
Ability of non-linear mixed models to predict growth in laying hens
Directory of Open Access Journals (Sweden)
Luis Fernando Galeano-Vasco
2014-11-01
Full Text Available In this study, the Von Bertalanffy, Richards, Gompertz, Brody, and Logistics non-linear mixed regression models were compared for their ability to estimate the growth curve in commercial laying hens. Data were obtained from 100 Lohmann LSL layers. The animals were identified and then weighed weekly from day 20 after hatch until they were 553 days of age. All the nonlinear models used were transformed into mixed models by the inclusion of random parameters. Accuracy of the models was determined by the Akaike and Bayesian information criteria (AIC and BIC, respectively, and the correlation values. According to AIC, BIC, and correlation values, the best fit for modeling the growth curve of the birds was obtained with Gompertz, followed by Richards, and then by Von Bertalanffy models. The Brody and Logistic models did not fit the data. The Gompertz nonlinear mixed model showed the best goodness of fit for the data set, and is considered the model of choice to describe and predict the growth curve of Lohmann LSL commercial layers at the production system of University of Antioquia.
Skill Acquisition Curves and Military Training
1986-01-01
group acquisition curves had one of two general shapes, either logarithmic (power function) or semi- logarithmic (exponential), including variants...is, so far as we aware, no inherent advantage to the use of equations in linear or logarithmic form other than that the display of fitted curves in...implications for the expected form of the acquisition curve . As Mazur and Hastie (1978) note, accumulation models yield the hyperbola (a power law
Directory of Open Access Journals (Sweden)
Florent Baty
2016-06-01
Full Text Available Abstract Background The six-minute walk test (6MWT is commonly used to quantify exercise capacity in patients with several cardio-pulmonary diseases. Oxygen uptake ( V ̇ $\\dot {\\mathrm {V}}$ O2 kinetics during 6MWT typically follow 3 distinct phases (rest, exercise, recovery that can be modeled by nonlinear regression. Simultaneous modeling of multiple kinetics requires nonlinear mixed models methodology. To the best of our knowledge, no such curve-fitting approach has been used to analyze multiple V ̇ $\\dot {\\mathrm {V}}$ O2 kinetics in both research and clinical practice so far. Methods In the present study, we describe functionality of the R package medrc that extends the framework of the commonly used packages drc and nlme and allows fitting nonlinear mixed effects models for automated nonlinear regression modeling. The methodology was applied to a data set including 6MWT V ̇ $\\dot {\\mathrm {V}}$ O2 kinetics from 61 patients with chronic obstructive pulmonary disease (disease severity stage II to IV. The mixed effects approach was compared to a traditional curve-by-curve approach. Results A six-parameter nonlinear regression model was jointly fitted to the set of V ̇ $\\dot {\\mathrm {V}}$ O2 kinetics. Significant differences between disease stages were found regarding steady state V ̇ $\\dot {\\mathrm {V}}$ O2 during exercise, V ̇ $\\dot {\\mathrm {V}}$ O2 level after recovery and V ̇ $\\dot {\\mathrm {V}}$ O2 inflection point in the recovery phase. Estimates obtained by the mixed effects approach showed standard errors that were consistently lower as compared to the curve-by-curve approach. Conclusions Hereby we demonstrate the novelty and usefulness of this methodology in the context of physiological exercise testing.
Agneter, E; Singer, E A; Sauermann, W; Feuerstein, T J
1997-09-01
The present work was stimulated by findings of a large reserve of presynaptic alpha2-autoreceptors in rat neocortex by different investigators and our own group, using classical models of receptor agonism. The mathematical background of these classical models seems erroneous since the asymmetry that spare receptors introduce into concentration-response curves is not considered appropriately. This asymmetry leads to a steepening of curve fits based on the logistic function. Therefore, the slope parameter c of a logistically fitted concentration-response curve can be used as a touchstone for the existence of spare receptors. Spare receptors induce a c > 1. Concentration-response data of the alpha2-autoreceptor-mediated inhibition of evoked [3H]-noradrenaline release in rat neocortex slices were re-analysed. The estimates of the slope parameter c of logistically fitted concentration-response curves obtained after treatment of rats with either vehicle or N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) to achieve an irreversible inactivation of alpha2-autoreceptors, were not compatible with the existence of a large receptor reserve. A model for nonlinear regression analysis developed under the a priori assumption of spare receptors confirmed the absence of spare receptors. Evaluation methods which neglect the alteration of the geometrical form of concentration-response curves due to non-proportionality between receptor occupation and relative response do not seem appropriate to quantify spare receptors. These methods may detect spare receptors where they do not exist.
Nonlinear Structured Growth Mixture Models in Mplus and OpenMx
Grimm, Kevin J.; Ram, Nilam; Estabrook, Ryne
2014-01-01
Growth mixture models (GMMs; Muthén & Muthén, 2000; Muthén & Shedden, 1999) are a combination of latent curve models (LCMs) and finite mixture models to examine the existence of latent classes that follow distinct developmental patterns. GMMs are often fit with linear, latent basis, multiphase, or polynomial change models because of their common use, flexibility in modeling many types of change patterns, the availability of statistical programs to fit such models, and the ease of programming. In this paper, we present additional ways of modeling nonlinear change patterns with GMMs. Specifically, we show how LCMs that follow specific nonlinear functions can be extended to examine the presence of multiple latent classes using the Mplus and OpenMx computer programs. These models are fit to longitudinal reading data from the Early Childhood Longitudinal Study-Kindergarten Cohort to illustrate their use. PMID:25419006
Nonlinear Structured Growth Mixture Models in Mplus and OpenMx.
Grimm, Kevin J; Ram, Nilam; Estabrook, Ryne
2010-01-01
Growth mixture models (GMMs; Muthén & Muthén, 2000; Muthén & Shedden, 1999) are a combination of latent curve models (LCMs) and finite mixture models to examine the existence of latent classes that follow distinct developmental patterns. GMMs are often fit with linear, latent basis, multiphase, or polynomial change models because of their common use, flexibility in modeling many types of change patterns, the availability of statistical programs to fit such models, and the ease of programming. In this paper, we present additional ways of modeling nonlinear change patterns with GMMs. Specifically, we show how LCMs that follow specific nonlinear functions can be extended to examine the presence of multiple latent classes using the Mplus and OpenMx computer programs. These models are fit to longitudinal reading data from the Early Childhood Longitudinal Study-Kindergarten Cohort to illustrate their use.
Nonlinear hyperbolic waves in multidimensions
Prasad, Phoolan
2001-01-01
The propagation of curved, nonlinear wavefronts and shock fronts are very complex phenomena. Since the 1993 publication of his work Propagation of a Curved Shock and Nonlinear Ray Theory, author Phoolan Prasad and his research group have made significant advances in the underlying theory of these phenomena. This volume presents their results and provides a self-contained account and gradual development of mathematical methods for studying successive positions of these fronts.Nonlinear Hyperbolic Waves in Multidimensions includes all introductory material on nonlinear hyperbolic waves and the theory of shock waves. The author derives the ray theory for a nonlinear wavefront, discusses kink phenomena, and develops a new theory for plane and curved shock propagation. He also derives a full set of conservation laws for a front propagating in two space dimensions, and uses these laws to obtain successive positions of a front with kinks. The treatment includes examples of the theory applied to converging wavefronts...
Fitness Club
2012-01-01
Get in Shape for Summer with the CERN Fitness Club Saturday 23 June 2012 from 14:30 to 16.30 (doors open at 14.00) Germana’s Fitness Workshop. Build strength and stamina, sculpt and tone your body and get your heart pumping with Germana’s workout mixture of Cardio Attack, Power Pump, Power Step, Cardio Combat and Cross-Training. Where: 216 (Pump room – equipped with changing rooms and showers). What to wear: comfortable clothes and indoor sports shoes + bring a drink! How much: 15 chf Sign up here: https://espace.cern.ch/club-fitness/Lists/Test_Subscription/NewForm.aspx? Join the Party and dance yourself into shape at Marco + Marials Zumba Masterclass. Saturday 30 June 2012 from 15:00 to 16:30 Marco + Mariel’s Zumba Masterclass Where: 216 (Pump room – equipped with changing rooms and showers). What to wear: comfortable clothes and indoor sports shoes + bring a drink! How much: 25 chf Sign up here: https://espace.cern.ch/club-fitness/Lists/Zumba%20...
Fitness Club
2012-01-01
The CERN Fitness Club is pleased to announce its new early morning class which will be taking place on: Tuesdays from 24th April 07:30 to 08:15 216 (Pump Hall, close to entrance C) – Facilities include changing rooms and showers. The Classes: The early morning classes will focus on workouts which will help you build not only strength and stamina, but will also improve your balance, and coordination. Our qualified instructor Germana will accompany you throughout the workout to ensure you stay motivated so you achieve the best results. Sign up and discover the best way to start your working day full of energy! How to subscribe? We invite you along to a FREE trial session, if you enjoy the activity, please sign up via our website: https://espace.cern.ch/club-fitness/Activities/SUBSCRIBE.aspx. * * * * * * * * Saturday 28th April Get in shape for the summer at our fitness workshop and zumba dance party: Fitness workshop with Germana 13:00 to 14:30 - 216 (Pump Hall) Price...
Fitness club
2013-01-01
Nordic Walking Classes Come join the Nordic walking classes and outings offered by the CERN Fitness Club starting September 2013. Our licensed instructor Christine offers classes for people who’ve never tried Nordic Walking and who would like to learn the technique, and outings for people who have completed the classes and enjoy going out as a group. Course 1: Tuesdays 12:30 - 13:30 24 September, 1 October, 8 October, 15 October Course 2: Tuesdays 12:30 - 13:30 5 November, 12 November, 19 November, 26 November Outings will take place on Thursdays (12:30 to 13:30) from 12 September 2013. We meet at the CERN Club Barracks car park (close to Entrance A) 10 minutes before departure. Prices: 50 CHF for 4 classes, including the 10 CHF Club membership. Payments made directly to instructor. Renting Poles: Poles can be rented from Christine at 5 CHF / hour. Subscription: Please subscribe at: http://cern.ch/club-fitness Looking forward to seeing you among us! Fitness Club FitnessClub@c...
Institute of Scientific and Technical Information of China (English)
郭志峰; 宋彩瑜; 郭婷婷; 何乾妹
2009-01-01
目的:用快原子轰击质谱(FAB-MS)建立一种川芎嗪定量分析的新方法.方法:以氘代甲醇为氘代试剂,激光照射0.5h得到的氘代川芎嗪为内标物;内标物与被测样品分子离子峰总离子流作非线性拟合,其初始峰强的比值与样品浓度呈线性,藉此对样品定量分析.质谱条件:快原子轰击源(FAB),仪器分辨率1000,枪压8kV,原子枪气Ar,底物为甘油.结果:氘代试剂用氘代甲醇,激光照射0.5 h下,氘代率为2.43%;以其作内标物,得到川芎嗪定最分析的工作曲线,线性方程为Y=6.75+2.24 X(r=0.9908),精密度RSD=2.9%.用此方法对磷酸川芎嗪片剂进行分析,给出了2种不同前处理方法的分析结果43.0 mg·片-1和45.0 mg·片-1.结论:快原子轰击质谱的非线性拟合法,是一种川芎嗪定量分析的新方法,该方法只需微克级样品,且干扰少,精度高.
Gilkey, Roderick; Kilts, Clint
2007-11-01
Recent neuroscientific research shows that the health of your brain isn't, as experts once thought, just the product of childhood experiences and genetics; it reflects your adult choices and experiences as well. Professors Gilkey and Kilts of Emory University's medical and business schools explain how you can strengthen your brain's anatomy, neural networks, and cognitive abilities, and prevent functions such as memory from deteriorating as you age. The brain's alertness is the result of what the authors call cognitive fitness -a state of optimized ability to reason, remember, learn, plan, and adapt. Certain attitudes, lifestyle choices, and exercises enhance cognitive fitness. Mental workouts are the key. Brain-imaging studies indicate that acquiring expertise in areas as diverse as playing a cello, juggling, speaking a foreign language, and driving a taxicab expands your neural systems and makes them more communicative. In other words, you can alter the physical makeup of your brain by learning new skills. The more cognitively fit you are, the better equipped you are to make decisions, solve problems, and deal with stress and change. Cognitive fitness will help you be more open to new ideas and alternative perspectives. It will give you the capacity to change your behavior and realize your goals. You can delay senescence for years and even enjoy a second career. Drawing from the rapidly expanding body of neuroscience research as well as from well-established research in psychology and other mental health fields, the authors have identified four steps you can take to become cognitively fit: understand how experience makes the brain grow, work hard at play, search for patterns, and seek novelty and innovation. Together these steps capture some of the key opportunities for maintaining an engaged, creative brain.
Parallel Parking Path Generation Based on Bezier Curve Fitting%基于Bezier曲线拟合的自主平行泊车轨迹模型仿真
Institute of Scientific and Technical Information of China (English)
刘钰; 马艳丽; 李涛
2011-01-01
The autonomous parking system is an intelligent tehnology to park a car into a small space. Based on Ackermann steering geometry, considering the parking practice, the minimum parking space and the bound of start point and collision-free space are obtained. Then based on Bezier curve. considering the dynamic constraint condition and the parametric equation, the dynamic relationship betwwen x and y ls eslablished. For each time point t, followed by a specific steering angle and turning radius, a new locaion can be obtained. So a car can be controlled to move along a Bezier curve, and finally the continuous path is generated. At last, the simulation based on Matlab shows that the car can not only avoid the obstaeles effectively, but also move smoothly on turning points. So the continuous auto-parking can be realized in a space as small as possible.%根据阿克曼转向几何学,联系实际泊车情况,首先给出最短泊车空间、泊车起始点范围以及避碰约束空间的生成方法,并在此基础上,考虑动力学约束条件,在直角坐标系Oxy平面中,利用参数化方程,基于Bezier曲线,建立x和y之间动态关系.对每个时间t,依次得到汽车泊车时的具体转向角度和转向半径,得到新的位置点,从而控制汽车沿着Bezier曲线随着时间做变速运动,最终实现连续曲率的轨迹规划.Matlab仿真表明,采用这种方法能够有效地实现避障,在曲线转折点处运动平滑,未出现抖动,满足自主泊车的连续性要求及所需泊车空间尽可能小的目的.
Institute of Scientific and Technical Information of China (English)
刘建涛; 杜平安
2012-01-01
提出一种拟合金属材料疲劳裂纹扩展试验数据,并计算疲劳裂纹扩展速度的通用方法.该方法采用递增的三次多项式函数拟合疲劳试验数据,并采用平均加权方式计算各局部函数拟合的结果,提高了试验数据的拟合精度和疲劳裂纹扩展速度的准确性.通过在疲劳裂纹长度和扩展速度拟合结果的加权计算过程中引入delta函数,该通用方法能够有效地拟合常幅和存在过载载荷的疲劳裂纹扩展试验数据,并计算各试验点的裂纹扩展速度,同时保证了三次多项式拟合过程的连续性.通过多组常幅和存在过载载荷的疲劳试验数据拟合和现有方法及扩展有限元预测结果的对比分析,验证了该通用方法的有效性.%A general approach of curve fitting of fatigue test data and calculation of fatigue crack growth rates is developed in the preceding paper. The approach uses five points incremental cubic function to fit the fatigue test data and adopts the average weighted method to deal with the fitting results, which improves the fitting accuracy of fatigue crack length and fatigue crack growth rates significantly. Furthermore, the delta function is introduced in the average process of fitting results to account for the retardation effect due to overloads, which makes the general approach be suitable for fitting the fatigue test data under constant amplitude loading and constant amplitude loading with interval overloads and guarantees the continuity of the fitting process. Several sets of fatigue test data and predictions of the existing approach and the extended finite element method are used to demonstrate the correctness and validity of the general approach, which shows great consistency.
Fitness Club
2012-01-01
Nordic Walking Classes Sessions of four classes of one hour each are held on Tuesdays. RDV barracks parking at Entrance A, 10 minutes before class time. Session 1 = 11.09 / 18.09 / 25.09 / 02.10, 18:15 - 19:15 Session 2 = 25.09 / 02.10 / 09.10 / 16.10, 12:30 - 13:30 Session 3 = 23.10 / 30.10 / 06.11 / 13.11, 12:30 - 13:30 Session 4 = 20.11 / 27.11 / 04.12 / 11.12, 12:30 - 13:30 Prices 40 CHF per session + 10 CHF club membership 5 CHF/hour pole rental Check out our schedule and enroll at http://cern.ch/club-fitness Hope to see you among us! fitness.club@cern.ch In spring 2012 there was a long-awaited progress in CERN Fitness club. We have officially opened a Powerlifting @ CERN, and the number of members of the new section has been increasing since then reaching 70+ people in less than 4 months. Powerlifting is a strength sport, which is simple as 1-2-3 and efficient. The "1-2-3" are the three basic lifts (bench press...
Corneal topography and soft contact lens fit.
Young, Graeme; Schnider, Cristina; Hunt, Chris; Efron, Suzanne
2010-05-01
To determine which ocular topography variables affect soft contact lens fit. Fifty subjects each wore three pairs of soft lenses in random succession (Vistakon Acuvue 2, Vistakon Acuvue Advance, Ciba Vision Night & Day), and various aspects of lens fit were evaluated. The steeper base curves of each type were worn in one eye and the flatter base curves in the other eye. Corneal topography data were collected using a Medmont E300 corneal topographer (Camberwell, Australia). Corneal curvature, shape factor (SF), and corneal height were measured over a 10 mm chord and also over the maximum measurable diameter. These were measured in the horizontal, vertical, steepest, and flattest meridians. With each lens type, the steeper base curve provided the best fit on the greatest proportion of eyes and the significant differences in various aspects of fit were noted between base curves. For each lens type, there was no significant difference in mean K-reading between those eyes best fit with the steeper base curve and those eyes best fit with the flatter base curve. Two of the lenses showed a positive correlation between centration and horizontal corneal height (maximum), whereas one lens showed a negative correlation between centration and horizontal SF (SF = e). Several lenses showed a positive correlation between post-blink movement and horizontal or vertical corneal SF. The measurement of corneal topography using current Placido disc instrumentation allows a better prediction of soft lens fit than by keratometry, but it is not reliable enough to enable accurate selection of the best fitting base curve. Some correlations are evident between corneal measurements; however, trial fitting remains the method of choice for selection of soft lens base curve.
The New Keynesian Phillips Curve
DEFF Research Database (Denmark)
Ólafsson, Tjörvi
This paper provides a survey on the recent literature on the new Keynesian Phillips curve: the controversies surrounding its microfoundation and estimation, the approaches that have been tried to improve its empirical fit and the challenges it faces adapting to the open-economy framework. The new...... Keynesian Phillips curve has been severely criticized for poor empirical dynamics. Suggested improvements involve making some adjustments to the standard sticky price framework, e.g. introducing backwardness and real rigidities, or abandoning the sticky price model and relying on models of inattentiveness......, learning or state-dependant pricing. The introduction of openeconomy factors into the new Keynesian Phillips curve complicate matters further as it must capture the nexus between price setting, inflation and the exchange rate. This is nevertheless a crucial feature for any model to be used for inflation...
Variability among polysulphone calibration curves
Energy Technology Data Exchange (ETDEWEB)
Casale, G R [University of Rome ' La Sapienza' , Physics Department, P.le A. Moro 2, I-00185, Rome (Italy); Borra, M [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy); Colosimo, A [University of Rome ' La Sapienza' , Department of Human Physiology and Pharmacology, P.le A. Moro 2, I-00185, Rome (Italy); Colucci, M [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy); Militello, A [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy); Siani, A M [University of Rome ' La Sapienza' , Physics Department, P.le A. Moro 2, I-00185, Rome (Italy); Sisto, R [ISPESL - Istituto Superiore per la Prevenzione E la Sicurezza del Lavoro, Occupational Hygiene Department, Via Fontana Candida 1, I-0040 Monteporzio Catone (RM) (Italy)
2006-09-07
Within an epidemiological study regarding the correlation between skin pathologies and personal ultraviolet (UV) exposure due to solar radiation, 14 field campaigns using polysulphone (PS) dosemeters were carried out at three different Italian sites (urban, semi-rural and rural) in every season of the year. A polysulphone calibration curve for each field experiment was obtained by measuring the ambient UV dose under almost clear sky conditions and the corresponding change in the PS film absorbance, prior and post exposure. Ambient UV doses were measured by well-calibrated broad-band radiometers and by electronic dosemeters. The dose-response relation was represented by the typical best fit to a third-degree polynomial and it was parameterized by a coefficient multiplying a cubic polynomial function. It was observed that the fit curves differed from each other in the coefficient only. It was assessed that the multiplying coefficient was affected by the solar UV spectrum at the Earth's surface whilst the polynomial factor depended on the photoinduced reaction of the polysulphone film. The mismatch between the polysulphone spectral curve and the CIE erythemal action spectrum was responsible for the variability among polysulphone calibration curves. The variability of the coefficient was related to the total ozone amount and the solar zenith angle. A mathematical explanation of such a parameterization was also discussed.
Fitness club
2013-01-01
Nordic Walking Classes New session of 4 classes of 1 hour each will be held on Tuesdays in May 2013. Meet at the CERN barracks parking at Entrance A, 10 minutes before class time. Dates and time: 07.05, 14.05, 21.05 and 28.05, fom 12 h 30 to 13 h 30 Prices: 40 CHF per session + 10 CHF club membership – 5 CHF / hour pole rental Check out our schedule and enroll at http://cern.ch/club-fitness Hope to see you among us!
Institute of Scientific and Technical Information of China (English)
廖小锋; 刘济明; 张东凯; 靳勇; 张勇; 闫国华; 王敏
2012-01-01
Several typical models of light-response curve of leaf net photosynthesis, such as non-rectangular hyperbolic model, rectangular hyperbolic model, prompted rectangular hyperbolic model and index function model, were tested on wild Drepanostachyum luodianense, and the applicability of these models also were investigated. The results were summarized as follows: ① the plant' t analytical solution of maximum net photosynmetic rate (Pnmax) and saturation point (Isat) couldn' t be solved by rectangular hyperbola model, non-rectangular hyperbola model and exponential equation model, while the values simulated by combining other methods existed a big difference compared with the measured value, and the data under photoinhibition couldn' t be processed by these three models; ② the quadratic polynomial model could process the data under photoinhibition to a certain extent, but the photosynthetic parameters simulated by it also existed larger difference compared with the measured value, even generated logic error, ③ the photosynthetic parameters simulated by modified rectangular hyperbola model all were close to the measured values ,and this model also could well process the data under photoinhibition; ④ the Pnmax, Isat compensation point(Ic), respiration rate(Rd) and initial quantum efticiency(a) of wild D. luodianense simulated by modified rectangular hyperbola model were 8.53 μmol·m-2s-1, 1 750.75 μmol·m-2s-1, 21.40 μmol·m-2s-1, 1.06 μmol·m-2s-1 and 0.054 respectively.%应用5种典型的光响应模型对野生小蓬竹叶片光响应曲线进行了拟合,并探讨了几种模型在光响应研究中的适用性.结果表明:①直角双曲线、非直角双曲线及指数函数模型无法求取植物最大净光合速率(Pnmax)和光饱和点(Isat)的解析解,而结合其它方法拟合的相应值却与实测值相差很大,同时也不能处理光抑制部分的光响应数据；②二次多项式模型能够一定程度地处理光抑制部分的光
Vibrational Analysis of Curved Single-Walled Carbon Nanotube on a Pasternak Elastic Foundation
DEFF Research Database (Denmark)
Mehdipour, I.; Barari, Amin; Kimiaeifar, Amin
2012-01-01
. By utilizing He’s Energy Balance Method (HEBM), the relationships of the nonlinear amplitude and frequency were expressed for a curved, single-walled carbon nanotube. The amplitude frequency response curves of the nonlinear free vibration were obtained for a curved, single-walled carbon nanotube embedded...
Method of construction spatial transition curve
Directory of Open Access Journals (Sweden)
S.V. Didanov
2013-04-01
Full Text Available Purpose. The movement of rail transport (speed rolling stock, traffic safety, etc. is largely dependent on the quality of the track. In this case, a special role is the transition curve, which ensures smooth insertion of the transition from linear to circular section of road. The article deals with modeling of spatial transition curve based on the parabolic distribution of the curvature and torsion. This is a continuation of research conducted by the authors regarding the spatial modeling of curved contours. Methodology. Construction of the spatial transition curve is numerical methods for solving nonlinear integral equations, where the initial data are taken coordinate the starting and ending points of the curve of the future, and the inclination of the tangent and the deviation of the curve from the tangent plane at these points. System solutions for the numerical method are the partial derivatives of the equations of the unknown parameters of the law of change of torsion and length of the transition curve. Findings. The parametric equations of the spatial transition curve are calculated by finding the unknown coefficients of the parabolic distribution of the curvature and torsion, as well as the spatial length of the transition curve. Originality. A method for constructing the spatial transition curve is devised, and based on this software geometric modeling spatial transition curves of railway track with specified deviations of the curve from the tangent plane. Practical value. The resulting curve can be applied in any sector of the economy, where it is necessary to ensure a smooth transition from linear to circular section of the curved space bypass. An example is the transition curve in the construction of the railway line, road, pipe, profile, flat section of the working blades of the turbine and compressor, the ship, plane, car, etc.
DEFF Research Database (Denmark)
Tan, Qihua; Thomassen, Mads; Hjelmborg, Jacob V B
2011-01-01
among fractional polynomial models with power terms from a set of fixed values that offer a wide range of curve shapes and suggests a best fitting model. After a limited simulation study, the model has been applied to our human in vivo irritated epidermis data with missing observations to investigate......-course pattern in a gene by gene manner. We introduce a growth curve model with fractional polynomials to automatically capture the various time-dependent expression patterns and meanwhile efficiently handle missing values due to incomplete observations. For each gene, our procedure compares the performances...... time-dependent transcriptional responses to a chemical irritant. Our method was able to identify the various nonlinear time-course expression trajectories. The integration of growth curves with fractional polynomials provides a flexible way to model different time-course patterns together with model...
A direct potential fitting RKR method: Semiclassical vs. quantal comparisons
Tellinghuisen, Joel
2016-12-01
Quantal and semiclassical (SC) eigenvalues are compared for three diatomic molecular potential curves: the X state of CO, the X state of Rb2, and the A state of I2. The comparisons show higher levels of agreement than generally recognized, when the SC calculations incorporate a quantum defect correction to the vibrational quantum number, in keeping with the Kaiser modification. One particular aspect of this is better agreement between quantal and SC estimates of the zero-point vibrational energy, supporting the need for the Y00 correction in this context. The pursuit of a direct-potential-fitting (DPF) RKR method is motivated by the notion that some of the limitations of RKR potentials may be innate, from their generation by an exact inversion of approximate quantities: the vibrational energy Gυ and rotational constant Bυ from least-squares analysis of spectroscopic data. In contrast, the DPF RKR method resembles the quantal DPF methods now increasingly used to analyze diatomic spectral data, but with the eigenvalues obtained from SC phase integrals. Application of this method to the analysis of 9500 assigned lines in the I2A ← X spectrum fails to alter the quantal-SC disparities found for the A-state RKR curve from a previous analysis. On the other hand, the SC method can be much faster than the quantal method in exploratory work with different potential functions, where it is convenient to use finite-difference methods to evaluate the partial derivatives required in nonlinear fitting.
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.
Research on physical shape preserving curve reconstruction
Institute of Scientific and Technical Information of China (English)
TANG Kelun; ZHANG Xiangwei; CHENG Siyuan; XIONG Hanwei; ZHANG Hong
2007-01-01
Fusion of various data is an effective way to improve the precision and efficiency of acquiring information in reverse engineering.A method of physical shape preserving curve reconstruction is proposed to better realize the data fusion of coordinate measuring machine (CMM) and visual information.From the principle of materials mechanics,the strain energy of the curve corresponding to the distortion is advanced as the internal energy,and the elastic potential energy of the curve is established,using a few precise measured data points as the equilibrium position,to be the external energy.On the basis of the principle of variation calculus,the basic spline finite element method (B-spline FEM) is used to determine the equilibrium position of curve deformation.Numerical simulation indicates that there is an extremely good agreement between the new fitted curve and the actual curve.
Multiphasic growth curve analysis.
Koops, W.J.
1986-01-01
Application of a multiphasic growth curve is demonstrated with 4 data sets, adopted from literature. The growth curve used is a summation of n logistic growth functions. Human height growth curves of this type are known as "double logistic" (n = 2) and "triple logistic" (n = 3) growth curves (Bock
Principal Curves on Riemannian Manifolds.
Hauberg, Soren
2016-09-01
Euclidean statistics are often generalized to Riemannian manifolds by replacing straight-line interpolations with geodesic ones. While these Riemannian models are familiar-looking, they are restricted by the inflexibility of geodesics, and they rely on constructions which are optimal only in Euclidean domains. We consider extensions of Principal Component Analysis (PCA) to Riemannian manifolds. Classic Riemannian approaches seek a geodesic curve passing through the mean that optimizes a criteria of interest. The requirements that the solution both is geodesic and must pass through the mean tend to imply that the methods only work well when the manifold is mostly flat within the support of the generating distribution. We argue that instead of generalizing linear Euclidean models, it is more fruitful to generalize non-linear Euclidean models. Specifically, we extend the classic Principal Curves from Hastie & Stuetzle to data residing on a complete Riemannian manifold. We show that for elliptical distributions in the tangent of spaces of constant curvature, the standard principal geodesic is a principal curve. The proposed model is simple to compute and avoids many of the pitfalls of traditional geodesic approaches. We empirically demonstrate the effectiveness of the Riemannian principal curves on several manifolds and datasets.
Burchardt, Malte; Träuble, Markus; Wittstock, Gunther
2009-06-15
The formalism for simulating scanning electrochemical microscopy (SECM) experiments by boundary element methods in three space coordinates has been extended to allow consideration of nonlinear boundary conditions. This is achieved by iteratively refining the boundary conditions that are encoded in a boundary condition matrix. As an example, the simulations are compared to experimental approach curves in the SECM feedback mode toward samples modified with glucose oxidase (GOx). The GOx layer was prepared by the layer-by-layer assembly of polyelectrolytes using glucose oxidase as one of the polyelectrolytes. The comparison of the simulated and experimental curves showed that under a wide range of experimentally accessible conditions approximations of the kinetics at the sample by first order models yield misleading results. The approach curves differ also qualitatively from curves calculated with first order models. As a consequence, this may lead to severe deviations when such curves are fitted to first order kinetic models. The use of linear approximations to describe the enzymatic reaction in SECM feedback experiments is justified only if the ratio of the mediator and Michaelis-Menten constant is equal to or smaller than 0.1 (deviation less than 10%).
Energy Technology Data Exchange (ETDEWEB)
Davis, C.G.
1990-01-01
The advent of nonlinear pulsation theory really coincides with the development of the large computers after the second world war. Christy and Stobbie were the first to make use of finite difference techniques on computers to model the bumps'' observed in the classical Cepheid light and velocity curves, the so-called Hertzsprung'' sequence. Following this work a more sophisticated analysis of the light and velocity curves from the models was made by Simon and Davis using Fourier techniques. Recently a simpler amplitude equation formalism has been developed that helps explain this resonance mechanism. The determination of Population I Cepheid masses by nonlinear methods will be discussed. For the lower mass objects, such as RR Lyrae and BL Her. stars, we find general agreement using evolutionary masses and nonlinear pulsation theory. An apparent difficulty of nonlinear pulsation theory occurs in the understanding of double'' mode pulsation, which will also be discussed. Recent studies in nonlinear pulsation theory have dealt with the question of mode selection, period doubling and the trends towards chaotic behavior such as is observed in the transition from W Virginis to RV Tauri-like stars. 10 refs., 1 fig., 2 tabs.
Confidence bounds for nonlinear dose-response relationships.
Baayen, C; Hougaard, P
2015-11-30
An important aim of drug trials is to characterize the dose-response relationship of a new compound. Such a relationship can often be described by a parametric (nonlinear) function that is monotone in dose. If such a model is fitted, it is useful to know the uncertainty of the fitted curve. It is well known that Wald confidence intervals are based on linear approximations and are often unsatisfactory in nonlinear models. Apart from incorrect coverage rates, they can be unreasonable in the sense that the lower confidence limit of the difference to placebo can be negative, even when an overall test shows a significant positive effect. Bootstrap confidence intervals solve many of the problems of the Wald confidence intervals but are computationally intensive and prone to undercoverage for small sample sizes. In this work, we propose a profile likelihood approach to compute confidence intervals for the dose-response curve. These confidence bounds have better coverage than Wald intervals and are more precise and generally faster than bootstrap methods. Moreover, if monotonicity is assumed, the profile likelihood approach takes this automatically into account. The approach is illustrated using a public dataset and simulations based on the Emax and sigmoid Emax models. Copyright © 2015 John Wiley & Sons, Ltd.
Experimental Simulation of Closed Timelike Curves
Ringbauer, Martin; Myers, Casey R; White, Andrew G; Ralph, Timothy C
2015-01-01
Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into non-linearities and the emergence of causal structures in quantum mechanics-essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the non-linear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of t...
Experimental simulation of closed timelike curves.
Ringbauer, Martin; Broome, Matthew A; Myers, Casey R; White, Andrew G; Ralph, Timothy C
2014-06-19
Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved, leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into nonlinearities and the emergence of causal structures in quantum mechanics--essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the nonlinear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction and the influence of decoherence.
There are four natural curves in the spinal column. The cervical, thoracic, lumbar, and sacral curvature. The curves, along with the intervertebral disks, help to absorb and distribute stresses that occur from everyday activities such as walking or from ...
Directory of Open Access Journals (Sweden)
Janusz Charatonik
1991-11-01
Full Text Available Results concerning contractibility of curves (equivalently: of dendroids are collected and discussed in the paper. Interrelations tetween various conditions which are either sufficient or necessary for a curve to be contractible are studied.
Parametrizing Algebraic Curves
Lemmermeyer, Franz
2011-01-01
We present the technique of parametrization of plane algebraic curves from a number theorist's point of view and present Kapferer's simple and beautiful (but little known) proof that nonsingular curves of degree > 2 cannot be parametrized by rational functions.
Motiei, H.; Jafari, A.; Naderali, R.
2017-02-01
In this paper, two chemically synthesized organic azo dyes, 2-(2,5-Dichloro-phenyazo)-5,5-dimethyl-cyclohexane-1,3-dione (azo dye (i)) and 5,5-Dimethyl-2-tolylazo-cyclohexane-1,3-dione (azo dye (ii)), have been studied from optical Kerr nonlinearity point of view. These materials were characterized by Ultraviolet-visible spectroscopy. Experiments were performed using a continous wave diode-pumped laser at 532 nm wavelength in three intensities of the laser beam. Nonlinear absorption (β), refractive index (n2) and third-order susceptibility (χ (3)) of dyes, were calculated. Nonlinear absorption coefficient of dyes have been calculated from two methods; 1) using theoretical fits and experimental data in the Z-scan technique, 2) using the strength of nonlinearity curves. The values of β obtained from both of the methods were approximately the same. The results demonstrated that azo dye (ii) displays better nonlinearity and has a lower two-photon absorption threshold than azo dye (i). Calculated parameter related to strength of nonlinearity for azo dye (ii) was higher than azo dye (i), It may be due to presence of methyl in azo dye (ii) instead of chlorine in azo dye (i). Furthermore, The measured values of third order susceptibility of azo dyes were from the order of 10-9 esu . These azo dyes can be suitable candidate for optical switching devices.
Institute of Scientific and Technical Information of China (English)
王倩茹; 陈红汉; 胡守志; 赵玉涛; 陈慧钦
2016-01-01
Curve-fitting analysis of micro FT-IR,in the theory of Gaussian,Lorentz function or their combination (Gaussian-Lorentz)model,can break through the limit of overlapping spectra resulting from complicated structures of samples (e.g.indi-vidual oil inclusion and bitumens).Hence,curve-fitting analysis of micro FT-IR was used for analyzing maturity of individual oil inclusion and the origin of bitumens in Shuntuoguole area of Tazhong northeastern slope systematically,and four conclusions have been obtained:firstly,curve-fitting analysis of micro FT-IR may be more accurate for calculating absorption peaks,and some easily neglected peaks can be detected by this method in contrast with the method of interval oriented by Pironon.Second-ly,Gaussian-Lorentz fitting is more approaching to actual spectra and the lower noise level is corresponding to better fit but re-quiring longer computation time.As a result,Gaussian-Lorentz fitting with 1~10 noise level is preferred.Thirdly,based on in-clusion system analysis and burial history projection with homogenization temperature,infrared parameters (e.g.CH2a/CH3a, Xinc and Xstd)reveal three hydrocarbon charging events occurred,including Late Caledonian,Late Hercynian and the Himala-ya.Finally,micro FT-IR is an effective means for analyzing multi-hydrocarbon charging events and complicated origin of bitu-mens undergoing biodegradation,oxidative degradation and water eluviation quantitatively in study area.%针对单个油包裹体和储层沥青等结构复杂样品傅里叶变换显微红外光谱吸收峰严重重叠的问题,基于高斯、洛伦茨函数或其组合(高斯-洛伦茨)模型理论,采用显微红外分峰拟合技术,对塔中北坡顺托果勒地区单个油包裹体成熟度和储层沥青成因进行了系统分析,并取得了4点认识:(1)通过与Pironon对合成油包裹体的峰位坐标区域化划分吸收峰对比,认为分峰拟合技术更为真实地反映各子峰的面积,而且能够识别重叠区
Morphing ab initio potential energy curve of beryllium monohydride
Špirko, Vladimír
2016-12-01
Effective (mass-dependent) potential energy curves of the ground electronic states of 9BeH, 9BeD, and 9BeT are constructed by morphing a very accurate MR-ACPF ab initio potential of Koput (2011) within the framework of the reduced potential energy curve approach of Jenč (1983). The morphing is performed by fitting the RPC parameters to available experimental ro-vibrational data. The resulting potential energy curves provide a fairly quantitative reproduction of the fitted data. This allows for a reliable prediction of the so-far unobserved molecular states in terms of only a small number of fitting parameters.
Chaotic Feature in the Light Curve of 3C 273
Institute of Scientific and Technical Information of China (English)
Lei Liu
2006-01-01
Some nonlinear dynamical techniques, including state-space reconstruction and correlation integral, are used to analyze the light curve of 3C 273. The result is compared with a chaotic model. The similarities between them suggest there is a low-dimension chaotic attractor in the light curve of 3C 273.
Properties of Rasch residual fit statistics.
Wu, Margaret; Adams, Richard J
2013-01-01
This paper examines the residual-based fit statistics commonly used in Rasch measurement. In particular, the paper analytically examines some of the theoretical properties of the residual-based fit statistics with a view to establishing the inferences that can be made using these fit statistics. More specifically, the relationships between the distributional properties of the fit statistics and sample size are discussed; some research that erroneously concludes that residual-based fit statistics are unstable is reviewed; and finally, it is analytically illustrated that, for dichotomous items, residual-based fit statistics provide a measure of the relative slope of empirical item characteristic curves. With a clear understanding of the theoretical properties of the fit statistics, the use and limitations of these statistics can be placed in the right light.
Institute of Scientific and Technical Information of China (English)
程冬兵; 张平仓; 赵健; 蔡崇法
2009-01-01
Soil water retention curve is one of the important soil hydrodynamics parameters in quantitative study of soil water retention and movement,which can reflect the basic properties of soil,such as water retention,water supply,and water availability,et al. In this thesis,characters of purple soil water retention curves under different measures of soil and water conservation were discussed,through analyzing soil water retention curves under contour hedgerow-intercroping system and rock ridge terrace-intercroping system. Then the measured datas were taken to fit four common soil water retention curve models respectively,in order to select the best model for the purple soil in the Three Gorges Reservoir Area. The results showed that the difference of purple soil water retention among different treatments could be observed easily. Based on the same soil water suction,soil water content was the highest for contour hedgerow treatment,secondly for rock ridge terrace treatment,and the lowest for the control. With the increase of soil water suction,the difference among treatments was more obvious. Both Gardner model and van Genuchten model were suitable for expressing purple soil water retention curve. According to practical needs,one of them could be selected. Generally, Gardner model was suitable for simple and quick field soil water management, and van Genuchten model was suitable for soil hydraulic properties estimation and application.%土壤水分特征曲线是反映土壤持水性、供水性及水分有效性等基本特性的重要曲线,是定量研究土壤水滞留与运移十分重要的土壤水动力学参数之一.通过分析比较等高绿篱农业系统和石坎梯田农业系统的紫色土水分特征曲线,探讨不同水保措施下紫色土水分特征曲线特征,将实测数据对国内外常见的几种土壤水分特征曲线模型分别进行拟合,并优选一种适合三峡库区紫色土的水分特征曲线模型.结果表明:不同处理紫
DEFF Research Database (Denmark)
Bernstein, Daniel J.; Birkner, Peter; Lange, Tanja;
2013-01-01
This paper introduces EECM-MPFQ, a fast implementation of the elliptic-curve method of factoring integers. EECM-MPFQ uses fewer modular multiplications than the well-known GMP-ECM software, takes less time than GMP-ECM, and finds more primes than GMP-ECM. The main improvements above the modular......-arithmetic level are as follows: (1) use Edwards curves instead of Montgomery curves; (2) use extended Edwards coordinates; (3) use signed-sliding-window addition-subtraction chains; (4) batch primes to increase the window size; (5) choose curves with small parameters and base points; (6) choose curves with large...
Picard groups of differential operators on curves
Wilson, George
2010-01-01
Let X be a complex affine curve (not isomorphic to the affine line), and let Pic(D) be the group of autoequivalences of the category of D(X)-modules. Cannings and Holland have shown that Pic(D) fits into an exact sequence in which the other groups can be considered known: we show that this sequence is split.
CHAOTIC TRANSIENTS IN A CURVED FLUID CONVEYING TUBE
Institute of Scientific and Technical Information of China (English)
Ni Qiao; Wang Lin; Qian Qin
2005-01-01
The chaotic transients of a curved fluid conveying tube subjected to a nonlinear foundation are investigated. The assumption of the inextensibility of the tube is applied to derive the nonlinear differential equation of motion via the Newtonian approach, with the differential quadrature method used to discretize the curved tube model in the spatial domain. And the nonlinear dynamic motion equation is obtained. The numerical analysis shows that, the final steady states are sensitive to the initial system conditions in a large parameter region of the fluid speed. This phenomenon of chaotic transients is infrequent for fluid conveying tubes.
Directory of Open Access Journals (Sweden)
Lara Toledo Henriques
2011-06-01
Full Text Available Procurou-se avaliar a precisão de cinco modelos não-lineares em descrever a forma da curva de produção de leite de vacas Nelore e o efeito do consumo voluntário (CV da vaca e do bezerro sobre a produção de leite (PL. Foram testados os modelos de Sikka, Nelder, Wood, Jenkins & Ferrell, e Jenkins & Ferrell com um parâmetro de ajustamento. Foram utilizadas 12 vacas primíparas com peso corporal médio de 359 kg (± 8 e seus respectivos bezerros. A produção de leite foi estimada pela pesagem do bezerro antes e após a mamada, do nascimento aos 180 dias de idade. As pesagens foram efetuadas duas vezes ao dia, semanalmente, após 6 horas de jejum de líquido e sólidos. Os modelos não-lineares de Sikka, Jenkins & Ferrell, Nelder e Wood não descreveram a curva de lactação apropriada devido ao excesso ou subestimação d o pico da produção de leite. O melhor ajustamento foi encontrado para o modelo de Jenkins & Ferrell com um parâmetro de ajustamento. O efeito do consumo voluntário da vaca e do bezerro, avaliado separadamente, não se correlacionou com a produção de leite. Entretanto, ao avaliar o consumo da vaca e do bezerro conjuntamente, foi encontrada uma correlação positiva e negativa com a produção de leite, respectivamente. A produção de leite está intimamente correlacionada com o consumo da vaca e do bezerro, e a capacidade de ingerir sólidos não lácteos reulta na redução da necessidade de leite da mãe.This research was carried out to evaluate five non-linear mathematical models to describe lactation curves of Nelore cows and effect of the cow and calf intake on milk yield. In this study we compared the models of Sikka (1950, Nelder (1966, Wood (1967, Jenkins & Ferrell (1984 and Jenkins & Ferrell (1984 with a fit parameter. Data of production were collected from 12 primiparous cows with a mean live weight of 359 kg (± 8 and its offspring. The milk production was estimated weighing the calf before and after
Institute of Scientific and Technical Information of China (English)
张小红; 王金萍; 王如瑛
2015-01-01
Objective To investigate the diagnostic value of contrast ultrasound and curve of gamma fitting in superficial cervical lymph nodes diseases. Methods Sixty patients, who were scheduled for superficial cervical lymph node excision or needle biopsy in our hospital, were included as the subjects in the study. All the patients were examined by two-dimensional, color doppler ultrasound and ultrasound contrast before the operation. And the lesion features and parameters were found and recorded. The sensitivity, specificity and accuracy of using ultrasound contrast in the diagnosis of benign and malignant (metastatic) lymph nodes were analyzed on the basis of the pathological re-sults of the operation, which was the gold standard for diagnosis. Results ①Twenty-nine benign cases and 31 ma-lignant metastatic cases among 60 of superficial lymph nodes were confirmed by pathological diagnosis. ②The result of ultrasound contrast showed that the benign lymph nodes mainly appeared evenly significant perfusion (24/29);while malignant metastatic lymph nodes mainly appeared uneven hypertransfusion (22/31) or uneven hypoperfusion (5/31).③The quantitative analysis of time intensity curve of gamma fitting was traced automatically by Q-LAB software. The peak intensity (PI), basic intensity (C), curve ascending slope (A), and area under curve (AUC) in the benign lymph nodes group were significantly higher than those in the malignant metastatic lymph nodes group ( P<0.05). The rise time (RT), time to peak (TTP), mean transit time (mTT), and the time of half concentration (T1/2) in the benign lymph nodes group were lower than those in the malignant metastasis lymph nodes group ( P<0.01). The sensitivity, specificity and accuracy of using ultrasound contrast in the diagnosis of benign and malignant (metastatic) lymph nodes were 87%, 83% and 85%, respectively. Conclusion The perfusion characteristics of the superficial cervical lymph nodes after the lymphadenography and the
Bloembergen, Nicolaas
1996-01-01
Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe
Rashidian Vaziri, Mohammad Reza
2013-07-10
In this paper, the Z-scan theory for nonlocal nonlinear media has been further developed when nonlinear absorption and nonlinear refraction appear simultaneously. To this end, the nonlinear photoinduced phase shift between the impinging and outgoing Gaussian beams from a nonlocal nonlinear sample has been generalized. It is shown that this kind of phase shift will reduce correctly to its known counterpart for the case of pure refractive nonlinearity. Using this generalized form of phase shift, the basic formulas for closed- and open-aperture beam transmittances in the far field have been provided, and a simple procedure for interpreting the Z-scan results has been proposed. In this procedure, by separately performing open- and closed-aperture Z-scan experiments and using the represented relations for the far-field transmittances, one can measure the nonlinear absorption coefficient and nonlinear index of refraction as well as the order of nonlocality. Theoretically, it is shown that when the absorptive nonlinearity is present in addition to the refractive nonlinearity, the sample nonlocal response can noticeably suppress the peak and enhance the valley of the Z-scan closed-aperture transmittance curves, which is due to the nonlocal action's ability to change the beam transverse dimensions.
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.
Comparing non-linear mathematical models to describe growth of different animals
Directory of Open Access Journals (Sweden)
Jhony Tiago Teleken
2017-02-01
Full Text Available The main objective of this study was to compare the goodness of fit of five non-linear growth models, i.e. Brody, Gompertz, Logistic, Richards and von Bertalanffy in different animals. It also aimed to evaluate the influence of the shape parameter on the growth curve. To accomplish this task, published growth data of 14 different groups of animals were used and four goodness of fit statistics were adopted: coefficient of determination (R2, root mean square error (RMSE, Akaike information criterion (AIC and Bayesian information criterion (BIC. In general, the Richards growth equation provided better fits to experimental data than the other models. However, for some animals, different models exhibited better performance. It was obtained a possible interpretation for the shape parameter, in such a way that can provide useful insights to predict animal growth behavior.
Topological Field Theory and Rational Curves
Aspinwall, Paul S; Aspinwall, Paul S.; Morrison, David R.
1993-01-01
We analyze the superstring propagating on a Calabi-Yau threefold. This theory naturally leads to the consideration of Witten's topological non-linear sigma-model and the structure of rational curves on the Calabi-Yau manifold. We study in detail the case of the world-sheet of the string being mapped to a multiple cover of an isolated rational curve and we show that a natural compactification of the moduli space of such a multiple cover leads to a formula in agreement with a conjecture by Candelas, de la Ossa, Green and Parkes.
Institute of Scientific and Technical Information of China (English)
李萍; 李凤华; 方华; 顾莉红; 杜晶; 黄翼然
2009-01-01
目的 评估超声造影伽马拟合分析技术对肾脏肿瘤微循环血流灌注定量分析的价值.方法 对50例肾脏实质内占位性病灶进行超声造影,将经DICOM3.0格式保存的动态图像导入SW-UCS-1型超声分析软件进行脱机分析,根据时间-强度曲线(TIC),得到上升支斜率(a3)、下降支曲率(a2)、达到时间(AT)、达峰时间(TTP)、基础强度(BI)、峰值强度、增强强度(AMP)、曲线下面积(AUC)、平均通过时间(MTT)、灌注指数(PI)等,并比较定量参数在肾脏恶性肿瘤和肾脏血管平滑肌脂肪瘤之间的差异.结果 肾脏恶性肿瘤多见灌注模式为快进快出,而慢进慢出多见于肾脏血管平滑肌脂肪瘤.肾脏恶性肿瘤和肾脏血管平滑肌脂肪瘤灌注模式分别为:快进快出28例和0例,快进慢出4例和1例,慢进快出5例和1例,慢进慢出1例和10例.TIC分析定量参数a3、AUC和PI在肾脏良恶性肿瘤比较中差异有统计学意义(P<0.05).结论 超声造影伽马拟合分析技术可以对肿瘤微循环血流灌注进行定量分析,有助于肾脏良恶性肿瘤鉴别.%Objective To evaluate the role of gamma curve fitting technique of contrast-enhanced ultrasound in quantitative analysis of microcirculation in renal solid lesions. Methods A total of fifty patients with renal parenchyma solid lesions were performed contrast-enhanced ultrasound. The images were analysed by computer with gamma fitting analysis of contrast-enhanced ultrasonic system. The quantitative parameters were obtained by the time-intensity curves, such as ascending slope (a3), descending slope (a2), arrival time (AT), time to peak intensity (TTP), basic intensity (BI), peak intensity, amplification (AMP), area under the curve (AUC), mean transit time (MTT) and perfusion index (PI). The parameters were compared between renal malignant and benign solid lesions. Results Fast-in and fast-out was the main perfusion mode in renal malignant tumors while slow-in and
Modelling Growth Curves in a Nondescript Italian Chicken Breed
National Research Council Canada - National Science Library
Maria Selvaggi; Vito Laudadio; Cataldo Dario; Vincenzo Tufarelli
2015-01-01
... it. This study was carried out to estimate the parameters of logistic, Gompertz and Richards growth curve models in a nondescript chicken breed population from southern Italy to determine the goodness of fit...
Coppens, Marc
2011-01-01
We consider coverings of real algebraic curves to real rational algebraic curves. We show the existence of such coverings having prescribed topological degree on the real locus. From those existence results we prove some results on Brill-Noether Theory for pencils on real curves. For coverings having topological degree 0 we introduce the covering number k and we prove the existence of coverings of degree 4 with prescribed covering number.
Directory of Open Access Journals (Sweden)
René Pellissier
2012-01-01
Full Text Available This paper explores the notion ofjump ing the curve,following from Handy 's S-curve onto a new curve with new rules policies and procedures. . It claims that the curve does not generally lie in wait but has to be invented by leadership. The focus of this paper is the identification (mathematically and inferentially ofthat point in time, known as the cusp in catastrophe theory, when it is time to change - pro-actively, pre-actively or reactively. These three scenarios are addressed separately and discussed in terms ofthe relevance ofeach.
Fit for purpose: Australia's National Fitness Campaign.
Collins, Julie A; Lekkas, Peter
2011-12-19
During a time of war, the federal government passed the National Fitness Act 1941 to improve the fitness of the youth of Australia and better prepare them for roles in the armed services and industry. Implementation of the National Fitness Act made federal funds available at a local level through state-based national fitness councils, which coordinated promotional campaigns, programs, education and infrastructure for physical fitness, with volunteers undertaking most of the work. Specifically focused on children and youth, national fitness councils supported the provision of children's playgrounds, youth clubs and school camping programs, as well as the development of physical education in schools and its teaching and research in universities. By the time the Act was repealed in 1994, fitness had become associated with leisure and recreation rather than being seen as equipping people for everyday life and work. The emergence of the Australian National Preventive Health Agency Act 2010 offers the opportunity to reflect on synergies with its historic precedent.
Characterization of commercial and biological growth curves in the Segureña sheep breed.
Lupi, T M; Nogales, S; León, J M; Barba, C; Delgado, J V
2015-08-01
Non-linear models were analysed to describe both the biological and commercial growth curves of the Segureña sheep, one of the most important Spanish breeds. We evaluated Brody, von Bertalanffy, Verhulst, logistic and Gompertz models, using historical data from the National Association of Segureña Sheep Breeders (ANCOS). These records were collected between 2000 and 2013, from a total of 129 610 weight observations ranging from birth to adulthood. The aim of this research was to establish the mathematical behaviour of body development throughout this breed's commercial life (birth to slaughter) and biological life (birth to adulthood); comparison between both slopes gives important information regarding the best time for slaughter, informs dietary advice according to animals' needs, permits economical predictions of productions and, by using the curve parameters as selection criteria, enables improvements in growth characteristics of the breed. Models were fitted according to the non-linear regression procedure of statistical package SPSS version19. Model parameters were estimated using the Levenberg-Marquardt algorithm. Candidate models were compared using the determinative coefficient, mean square error, number of iterations, Akaike information coefficient and biological coherence of the estimated parameters. The von Bertalanffy and logistic models were found to be best suited to the biological and commercial growth curves, respectively, for both sexes. The Brody equation was found to be unsuitable for studying the commercial growth curve. Differences between the parameters in both sexes indicate a strong impact of sexual dimorphism on growth. This can emphasize the value of the highest growth rate for females, indicating that they reach maturity earlier.
Afterglow Light Curves and Broken Power Laws: A Statistical Study
J'ohannesson, G; Gudmundsson, E H; J\\'ohannesson, Gudlaugur; Bj\\"ornsson, Gunnlaugur; Gudmundsson, Einar H.
2006-01-01
In gamma-ray burst research it is quite common to fit the afterglow light curves with a broken power law to interpret the data. We apply this method to a computer simulated population of afterglows and find systematic differences between the known model parameters of the population and the ones derived from the power law fits. In general, the slope of the electron energy distribution is overestimated from the pre-break light curve slope while being underestimated from the post-break slope. We also find that the jet opening angle derived from the fits is overestimated in narrow jets and underestimated in wider ones. Results from fitting afterglow light curves with broken power laws must therefore be interpreted with caution since the uncertainties in the derived parameters might be larger than estimated from the fit. This may have implications for Hubble diagrams constructed using gamma-ray burst data.
Halpha rotation curves the soft core question
Marchesini, D; Chincarini, G L; Firmani, C; Conconi, P; Molinari, E; Zacchei, A
2002-01-01
We present good resolution Halpha rotation curves of 6 galaxies: late-type dwarf and low surface brightness galaxies (LSB) for which accurate HI rotation curves are available from the literature. Observations are carried out at Telescopio Nazionale Galileo (TNG). For LSB F583-1 an innovative dispersing element was used, the Volume Phase Holographic (VPH) with a dispersion of about 0.35 A pxl^{-1}. From our analysis we find good agreement between the Halpha data and the HI observations concluding that the HI data for these galaxies suffer very little from beam smearing. We show that the optical rotation curves of these dark matter dominated galaxies are best fitted by the Burkert profile. In the center of galaxies, where the N-body simulations predict cusp cores and fast rising rotation curves, our data seem to be in better agreement with the presence of soft cores.
Institute of Scientific and Technical Information of China (English)
金蔚青; 蔡丽霞; 潘志雷; 长岛敏夫; 蒋元方; 依田真一
2001-01-01
A method for measuring the surface tension—Contour Curve Fitting Method, which is determined by digital video image processing of a sessile drop with using computer was discussed. The image of a sessile drop of Li2B4O7+KNbO3 formed on a BN plate was recorded on a digital video tape and converted into digital data of profile by using the technique of digital image acqui sition and processing. The Segmented drop image was fitted with numerical solution of theoretical equations to determine a surface tension. The thermal and solute surface tension coefficients were given by the following forms respectively, γT(mN/m)＝210+0.15(T-900℃), 900℃＜ T＜1000℃and γc (mN/m)＝229-0.45(CKN-10wt%), 10wt%＜ CKN ＜30wt%.%讨论了一种表面张力测量方法一轮廓曲线吻合法。它是一种应用计算机技术，用数字图像信息处理液滴轮廓的方法。应用数字图像测量和信息处理技术，将置于氮化硼水平平板上的Li2B4O7+KNbO3液滴的轮廓图像记录在录像带上，然后转换成数字图像数据，并与理论方程的数值解吻合，求得表面张力系数。用这种方法侧得的Li2B4O7+KNbO3溶液的表面张力温度系数和表面张力溶质系数分别为γT(mN/m)＝210+0.15(T-900℃),900℃ T 1000℃;γc(mN/m)＝229-0.45(CKN--10wt％),10wt％ CKN 30wt％。
2016-07-01
Advanced Research Projects Agency (DARPA) Dynamics-Enabled Frequency Sources (DEFYS) program is focused on the convergence of nonlinear dynamics and...Early work in this program has shown that nonlinear dynamics can provide performance advantages. However, the pathway from initial results to...dependent nonlinear stiffness observed in these devices. This work is ongoing, and will continue through the final period of this program . Reference 9
Nayfeh, Ali Hasan
1995-01-01
Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim
Yoshida, Zensho
2010-01-01
This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl
Nanda, Sudarsan
2013-01-01
"Nonlinear analysis" presents recent developments in calculus in Banach space, convex sets, convex functions, best approximation, fixed point theorems, nonlinear operators, variational inequality, complementary problem and semi-inner-product spaces. Nonlinear Analysis has become important and useful in the present days because many real world problems are nonlinear, nonconvex and nonsmooth in nature. Although basic concepts have been presented here but many results presented have not appeared in any book till now. The book could be used as a text for graduate students and also it will be useful for researchers working in this field.
Nonlinear Creep Model for Deep Rock under High Stress and High Pore Water Pressure Condition
Directory of Open Access Journals (Sweden)
Xie Yuanguang
2016-05-01
Full Text Available Conventional triaxial compression creep experiments for deep sandstone under high confining pressure and high pore water pressure were carried out, in order to predict the creep response of deep rock under these conditions. A nonlinear viscoelastic-plastic creep constitutive model was proposed based on the experimental results. The theory of component model was used as a basis for the formulation of this model. First, by using mathematical fitting and analogy, a new nonlinear viscous component was introduced based on the properties of the creep curves during the tertiary stage. Second, a timer component to judge whether the creep can get into the tertiary stage was presented. Finally, a nonlinear creep model was proposed. Results showed good agreement between theory curves from the nonlinear creep model and experimental data. This model can be applied to predict deep rock creep responses under high stress and high pore water pressure conditions. Hence, the obtained conclusions in this study are beneficial to deep rock engineering.
Simulating Supernova Light Curves
Energy Technology Data Exchange (ETDEWEB)
Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-05-05
This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.
Tempo curves considered harmful
Desain, P.; Honing, H.
1993-01-01
In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression th
Pairings on hyperelliptic curves
Balakrishnan, Jennifer; Chisholm, Sarah; Eisentraeger, Kirsten; Stange, Katherine; Teske, Edlyn
2009-01-01
We assemble and reorganize the recent work in the area of hyperelliptic pairings: We survey the research on constructing hyperelliptic curves suitable for pairing-based cryptography. We also showcase the hyperelliptic pairings proposed to date, and develop a unifying framework. We discuss the techniques used to optimize the pairing computation on hyperelliptic curves, and present many directions for further research.
National Research Council Canada - National Science Library
Andreas Chai; Alessio Moneta
2010-01-01
..., Professor of Economics, University of Illinois, Chicago, at jpersky@uic.edu jpersky@uic.edu.. Introduction Introduction Engel curves describe how household expenditure on particular goods or Engel curves describe how household expenditure on particular goods or services depends on household income. The name comes from the German st...
Martínez, Sol Sáez; de la Rosa, Félix Martínez; Rojas, Sergio
2017-01-01
In Advanced Calculus, our students wonder if it is possible to graphically represent a tornado by means of a three-dimensional curve. In this paper, we show it is possible by providing the parametric equations of such tornado-shaped curves.
Chou, Kai-Seng
2001-01-01
Although research in curve shortening flow has been very active for nearly 20 years, the results of those efforts have remained scattered throughout the literature. For the first time, The Curve Shortening Problem collects and illuminates those results in a comprehensive, rigorous, and self-contained account of the fundamental results.The authors present a complete treatment of the Gage-Hamilton theorem, a clear, detailed exposition of Grayson''s convexity theorem, a systematic discussion of invariant solutions, applications to the existence of simple closed geodesics on a surface, and a new, almost convexity theorem for the generalized curve shortening problem.Many questions regarding curve shortening remain outstanding. With its careful exposition and complete guide to the literature, The Curve Shortening Problem provides not only an outstanding starting point for graduate students and new investigations, but a superb reference that presents intriguing new results for those already active in the field.
Cortazar, E; Usobiaga, A; Fernández, L A; de, Diego A; Madariaga, J M
2002-02-01
A MATHEMATICA package, 'CONDU.M', has been developed to find the polynomial in concentration and temperature which best fits conductimetric data of the type (kappa, c, T) or (kappa, c1, c2, T) of electrolyte solutions (kappa: specific conductivity; ci: concentration of component i; T: temperature). In addition, an interface, 'TKONDU', has been written in the TCL/Tk language to facilitate the use of CONDU.M by an operator not familiarised with MATHEMATICA. All this software is available on line (UPV/EHU, 2001). 'CONDU.M' has been programmed to: (i) select the optimum grade in c1 and/or c2; (ii) compare models with linear or quadratic terms in temperature; (iii) calculate the set of adjustable parameters which best fits data; (iv) simplify the model by elimination of 'a priori' included adjustable parameters which after the regression analysis result in low statistical significance; (v) facilitate the location of outlier data by graphical analysis of the residuals; and (vi) provide quantitative statistical information on the quality of the fit, allowing a critical comparison among different models. Due to the multiple options offered the software allows testing different conductivity models in a short time, even if a large set of conductivity data is being considered simultaneously. Then, the user can choose the best model making use of the graphical and statistical information provided in the output file. Although the program has been initially designed to treat conductimetric data, it can be also applied for processing data with similar structure, e.g. (P, c, T) or (P, c1, c2, T), being P any appropriate transport, physical or thermodynamic property.
ProFit: Bayesian galaxy fitting tool
Robotham, A. S. G.; Taranu, D.; Tobar, R.
2016-12-01
ProFit is a Bayesian galaxy fitting tool that uses the fast C++ image generation library libprofit (ascl:1612.003) and a flexible R interface to a large number of likelihood samplers. It offers a fully featured Bayesian interface to galaxy model fitting (also called profiling), using mostly the same standard inputs as other popular codes (e.g. GALFIT ascl:1104.010), but it is also able to use complex priors and a number of likelihoods.
Traction curves for the decohesion of covalent crystals
Enrique, Raúl A.; Van der Ven, Anton
2017-01-01
We study, by first principles, the energy versus separation curves for the cleavage of a family of covalent crystals with the diamond and zincblende structure. We find that there is universality in the curves for different materials which is chemistry independent but specific to the geometry of the particular cleavage plane. Since these curves do not strictly follow the universal binding energy relationship (UBER), we present a derivation of an extension to this relationship that includes non-linear force terms. This extended form of UBER allows for a flexible and practical mathematical description of decohesion curves that can be applied to the quantification of cohesive zone models.
Relative Locality in Curved Space-time
Kowalski-Glikman, Jerzy
2013-01-01
In this paper we construct the action describing dynamics of the particle moving in curved spacetime, with a non-trivial momentum space geometry. Curved momentum space is the core feature of theories where relative locality effects are presents. So far aspects of nonlinearities in momentum space have been studied only for flat or constantly expanding (De Sitter) spacetimes, relying on the their maximally symmetric nature. The extension of curved momentum space frameworks to arbitrary spacetime geometries could be relevant for the opportunities to test Planck-scale curvature/deformation of particles momentum space. As a first example of this construction we describe the particle with kappa-Poincar\\'e momentum space on a circular orbit in Schwarzschild spacetime, where the contributes of momentum space curvature turn out to be negligible. The analysis of this problem relies crucially on the solution of the soccer ball problem.
Directory of Open Access Journals (Sweden)
Paulo Prochno
2004-07-01
Full Text Available Learning curves have been studied for a long time. These studies provided strong support to the hypothesis that, as organizations produce more of a product, unit costs of production decrease at a decreasing rate (see Argote, 1999 for a comprehensive review of learning curve studies. But the organizational mechanisms that lead to these results are still underexplored. We know some drivers of learning curves (ADLER; CLARK, 1991; LAPRE et al., 2000, but we still lack a more detailed view of the organizational processes behind those curves. Through an ethnographic study, I bring a comprehensive account of the first year of operations of a new automotive plant, describing what was taking place on in the assembly area during the most relevant shifts of the learning curve. The emphasis is then on how learning occurs in that setting. My analysis suggests that the overall learning curve is in fact the result of an integration process that puts together several individual ongoing learning curves in different areas throughout the organization. In the end, I propose a model to understand the evolution of these learning processes and their supporting organizational mechanisms.
Parameterization for fitting triangular mesh
Institute of Scientific and Technical Information of China (English)
LIN Hongwei; WANG Guojin; LIU Ligang; BAO Hujun
2006-01-01
In recent years, with the development of 3D data acquisition equipments, the study on reverse engineering has become more and more important. However, the existing methods for parameterization can hardly ensure that the parametric domain is rectangular, and the parametric curve grid is regular. In order to overcome these limitations, we present a novel method for parameterization of triangular meshes in this paper. The basic idea is twofold: first, because the isotherms in the steady temperature do not intersect with each other, and are distributed uniformly, no singularity (fold-over) exists in the parameterization; second, a 3D harmonic equation is solved by the finite element method to obtain the steady temperature field on a 2D triangular mesh surface with four boundaries. Therefore, our proposed method avoids the embarrassment that it is impossible to solve the 2D quasi-harmonic equation on the 2D triangular mesh without the parametric values at mesh vertices. Furthermore, the isotherms on the temperature field are taken as a set of iso-parametric curves on the triangular mesh surface. The other set of iso-parametric curves can be obtained by connecting the points with the same chord-length on the isotherms sequentially. The obtained parametric curve grid is regular, and distributed uniformly, and can map the triangular mesh surface to the unit square domain with boundaries of mesh surface to boundaries of parametric domain, which ensures that the triangular mesh surface or point cloud can be fitted with the NURBS surface.
Least Squares Data Fitting with Applications
DEFF Research Database (Denmark)
Hansen, Per Christian; Pereyra, Víctor; Scherer, Godela
predictively. The main concern of Least Squares Data Fitting with Applications is how to do this on a computer with efficient and robust computational methods for linear and nonlinear relationships. The presentation also establishes a link between the statistical setting and the computational issues...... with problems of linear and nonlinear least squares fitting will find this book invaluable as a hands-on guide, with accessible text and carefully explained problems. Included are • an overview of computational methods together with their properties and advantages • topics from statistical regression analysis......As one of the classical statistical regression techniques, and often the first to be taught to new students, least squares fitting can be a very effective tool in data analysis. Given measured data, we establish a relationship between independent and dependent variables so that we can use the data...
Least Squares Data Fitting with Applications
DEFF Research Database (Denmark)
Hansen, Per Christian; Pereyra, Víctor; Scherer, Godela
As one of the classical statistical regression techniques, and often the first to be taught to new students, least squares fitting can be a very effective tool in data analysis. Given measured data, we establish a relationship between independent and dependent variables so that we can use the data...... predictively. The main concern of Least Squares Data Fitting with Applications is how to do this on a computer with efficient and robust computational methods for linear and nonlinear relationships. The presentation also establishes a link between the statistical setting and the computational issues...... with problems of linear and nonlinear least squares fitting will find this book invaluable as a hands-on guide, with accessible text and carefully explained problems. Included are • an overview of computational methods together with their properties and advantages • topics from statistical regression analysis...
Erickson, Tim
2008-01-01
We often look for a best-fit function to a set of data. This article describes how a "pretty good" fit might be better than a "best" fit when it comes to promoting conceptual understanding of functions. In a pretty good fit, students design the function themselves rather than choosing it from a menu; they use appropriate variable names; and they…
DEFF Research Database (Denmark)
Jensen, Jens-Ole
2003-01-01
Artiklen redegør for udbredelsen af fitness blandt unge og diskuterer, hvor det er blevet så populært at dyrke fitness.......Artiklen redegør for udbredelsen af fitness blandt unge og diskuterer, hvor det er blevet så populært at dyrke fitness....
Seeing How Fitting Process Works
Montalbano, Vera
2016-01-01
A common problem in teaching Physics in secondary school is due to the gap in terms of difficulty between the physical concepts and the mathematical tools which are necessary to study them quantitatively. Advanced statistical estimators are commonly introduced only a couple of years later than some common physical topics, such as e.g. the electronic circuit analysis. Filling this gap with alternative methods appears to be opportune, in order to let the students reach a full comprehension of the issue they are facing with. In this work we use a smartphone camera and GeoGebra to propose a visual method for understanding the physical meaning of a fitting process. The time constant of an RC circuit is estimated by fitting the discharge curve of a capacitor visualized on the screen of an oscilloscope.
A Theoretical Model for the Hormetic Dose-response Curve for Anticancer Agents.
Yoshimasu, Tatsuya; Ohashi, Takuya; Oura, Shoji; Kokawa, Yozo; Kawago, Mitsumasa; Hirai, Yoshimitsu; Miyasaka, Miwako; Nishiguchi, Haruka; Kawashima, Sayoko; Yata, Yumi; Honda, Mariko; Fujimoto, Takahiro; Okamura, Yoshitaka
2015-11-01
In the present article, we quantitatively evaluated the dose-response relationship of hormetic reactions of anticancer agents in vitro. Serial dilutions of gemcitabine, cisplatin, 5-fluorouracil, vinorelbine, and paclitaxel were administered to the A549 non-small-cell lung cancer cell line. The bi-phasic sigmoidal curve with hormetic and cytotoxic effects is given by the formula y=(a-b/(1+exp(c(*)log(x)-d)))/(1+exp(e(*)log(x)-f)), that was used to perform a non-linear least square regression. The dose-responses of the five anticancer agents were fitted to this equation. Gemcitabine and 5-fluorouracil, which had the lowest ED50 for their hormetic reaction, had the most pronounced promotive effects out of the five anticancer agents tested. The hormetic reaction progressed exponentially with culturing time. Our theoretical model will be useful in predicting how hormetic reactions affect patients with malignant tumors.
Non-linear canonical correlation
van der Burg, Eeke; de Leeuw, Jan
1983-01-01
Non-linear canonical correlation analysis is a method for canonical correlation analysis with optimal scaling features. The method fits many kinds of discrete data. The different parameters are solved for in an alternating least squares way and the corresponding program is called CANALS. An
U.S. Environmental Protection Agency — an UV calibration curve for SRHA quantitation. This dataset is associated with the following publication: Chang, X., and D. Bouchard. Surfactant-Wrapped Multiwalled...
Fitness World - Fremtidig overlevelse
Rice, Kasper; Klink, Nikolaj; Nielsen, Mie; Carlson, Andre; Boy, Mikkel; Hansen, Alexander
2015-01-01
Our project is a case study with Fitness World as a baseline. Our project will enhance Fitness Worlds penetration on their current position on the market. Our empiricism includes both qualitative and quantitative methodical approaches by the use of an expert interview and a questionnaire survey. These methods contribute and generate general knowledge about the fitness culture in Denmark and the customers in the fitness industry. We have stated a possible strategic opportunity for Fitness Worl...
Flow characteristics of curved ducts
Directory of Open Access Journals (Sweden)
Rudolf P.
2007-10-01
Full Text Available Curved channels are very often present in real hydraulic systems, e.g. curved diffusers of hydraulic turbines, S-shaped bulb turbines, fittings, etc. Curvature brings change of velocity profile, generation of vortices and production of hydraulic losses. Flow simulation using CFD techniques were performed to understand these phenomena. Cases ranging from single elbow to coupled elbows in shapes of U, S and spatial right angle position with circular cross-section were modeled for Re = 60000. Spatial development of the flow was studied and consequently it was deduced that minor losses are connected with the transformation of pressure energy into kinetic energy and vice versa. This transformation is a dissipative process and is reflected in the amount of the energy irreversibly lost. Least loss coefficient is connected with flow in U-shape elbows, biggest one with flow in Sshape elbows. Finally, the extent of the flow domain influenced by presence of curvature was examined. This isimportant for proper placement of mano- and flowmeters during experimental tests. Simulations were verified with experimental results presented in literature.
Localized Turing patterns in nonlinear optical cavities
Kozyreff, G.
2012-05-01
The subcritical Turing instability is studied in two classes of models for laser-driven nonlinear optical cavities. In the first class of models, the nonlinearity is purely absorptive, with arbitrary intensity-dependent losses. In the second class, the refractive index is real and is an arbitrary function of the intracavity intensity. Through a weakly nonlinear analysis, a Ginzburg-Landau equation with quintic nonlinearity is derived. Thus, the Maxwell curve, which marks the existence of localized patterns in parameter space, is determined. In the particular case of the Lugiato-Lefever model, the analysis is continued to seventh order, yielding a refined formula for the Maxwell curve and the theoretical curve is compared with recent numerical simulation by Gomila et al. [D. Gomila, A. Scroggie, W. Firth, Bifurcation structure of dissipative solitons, Physica D 227 (2007) 70-77.
Large Curved Surface Measurement
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The measurement principle of large curved surface through theodolite industry survey system is introduced. Two methods are suggested with respect to the distribution range of curved surface error. The experiments show that the measurement precision can be up to 0.15mm with relative precision of 3×10-5. Finally, something needed paying attention to and the application aspects on theodolite industry survey system are given.
2015-01-01
In this paper we consider an elementary, and largely unexplored, combinatorial problem in low-dimensional topology. Consider a real 2-dimensional compact surface $S$, and fix a number of points $F$ on its boundary. We ask: how many configurations of disjoint arcs are there on $S$ whose boundary is $F$? We find that this enumerative problem, counting curves on surfaces, has a rich structure. For instance, we show that the curve counts obey an effective recursion, in the general framework of to...
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
This is the note for a series of lectures that the author gave at the Centre de Recerca Matemtica (CRM), Bellaterra, Barcelona, Spain on October 19–24, 2009. The aim is to give a comprehensive description of some recent work of the author and his students on generalisations of the Gross-Zagier formula, Euler systems on Shimura curves, and rational points on elliptic curves.
Latent Growth Curve Models for Biomarkers of the Stress Response
Directory of Open Access Journals (Sweden)
John M. Felt
2017-06-01
Full Text Available Objective: The stress response is a dynamic process that can be characterized by predictable biochemical and psychological changes. Biomarkers of the stress response are typically measured over time and require statistical methods that can model change over time. One flexible method of evaluating change over time is the latent growth curve model (LGCM. However, stress researchers seldom use the LGCM when studying biomarkers, despite their benefits. Stress researchers may be unaware of how these methods can be useful. Therefore, the purpose of this paper is to provide an overview of LGCMs in the context of stress research. We specifically highlight the unique benefits of using these approaches.Methods: Hypothetical examples are used to describe four forms of the LGCM.Results: The following four specifications of the LGCM are described: basic LGCM, latent growth mixture model, piecewise LGCM, and LGCM for two parallel processes. The specifications of the LGCM are discussed in the context of the Trier Social Stress Test. Beyond the discussion of the four models, we present issues of modeling nonlinear patterns of change, assessing model fit, and linking specific research questions regarding biomarker research using different statistical models.Conclusions: The final sections of the paper discuss statistical software packages and more advanced modeling capabilities of LGCMs. The online Appendix contains example code with annotation from two statistical programs for the LCGM.
Inverse design of nonlinearity in energy harvesters for optimum damping
Ghandchi Tehrani, Maryam; Elliott, S. J.
2016-09-01
This paper presents the inverse design method for the nonlinearity in an energy harvester in order to achieve an optimum damping. A single degree-of-freedom electromechanical oscillator is considered as an energy harvester, which is subjected to a harmonic base excitation. The harvester has a limited throw due to the physical constraint of the device, which means that the amplitude of the relative displacement between the mass of the harvester and the base cannot exceed a threshold when the device is driven at resonance and beyond a particular amplitude. This physical constraint requires the damping of the harvester to be adjusted for different excitation amplitudes, such that the relative displacement is controlled and maintained below the limit. For example, the damping can be increased to reduce the amplitude of the relative displacement. For high excitation amplitudes, the optimum damping is, therefore, dependent on the amplitude of the base excitation, and can be synthesised by a nonlinear function. In this paper, a nonlinear function in the form of a bilinear is considered to represent the damping model of the device. A numerical optimisation using Matlab is carried out to fit a curve to the amplitude-dependent damping in order to determine the optimum bilinear model. The nonlinear damping is then used in the time-domain simulations and the relative displacement and the average harvested power are obtained. It is demonstrated that the proposed nonlinear damping can maintain the relative displacement of the harvester at its maximum level for a wide range of excitation, therefore providing the optimum condition for power harvesting.
Distribution of the nonlinear random ocean wave period
Institute of Scientific and Technical Information of China (English)
HOU Yijun; LI Mingjie; SONG Guiting; SI Guangcheng; QI Peng; HU Po
2009-01-01
Because of the intrinsic difficulty in determining distributions for wave periods, previous studies on wave period distribution models have not taken nonlinearity into account and have not performed well in terms of describing and statistically analyzing the probability density distribution of ocean waves. In this study, a statistical model of random waves is developed using Stokes wave theory of water wave dynamics. In addition, a new nonlinear probability distribution function for the wave period is presented with the parameters of spectral density width and nonlinear wave steepness, which is more reasonable as a physical mechanism. The magnitude of wave steepness determines the intensity of the nonlinear effect, while the spectral width only changes the energy distribution. The wave steepness is found to be an important parameter in terms of not only dynamics but also statistics. The value of wave steepness reflects the degree that the wave period distribution skews from the Cauchy distribution, and it also describes the variation in the distribution function, which resembles that of the wave surface elevation distribution and wave height distribution. We found that the distribution curves skew leftward and upward as the wave steepness increases. The wave period observations for the SZFII-1 buoy, made off the coast of Weihai (37°27.6′ N, 122°15.1′ E), China, are used to verify the new distribution. The coefficient of the correlation between the new distribution and the buoy data at different spectral widths (υ=0.3-0.5) is within the range of 0.968 6 to 0.991 7. In addition, the Longuet-Higgins (1975) and Sun (1988) distributions and the new distribution presented in this work are compared. The validations and comparisons indicate that the new nonlinear probability density distribution fits the buoy measurements better than the Longuet-Higgins and Sun distributions do. We believe that adoption of the new wave period distribution would improve traditional
Highly curved microchannel plates
Siegmund, O. H. W.; Cully, S.; Warren, J.; Gaines, G. A.; Priedhorsky, W.; Bloch, J.
1990-01-01
Several spherically curved microchannel plate (MCP) stack configurations were studied as part of an ongoing astrophysical detector development program, and as part of the development of the ALEXIS satellite payload. MCP pairs with surface radii of curvature as small as 7 cm, and diameters up to 46 mm have been evaluated. The experiments show that the gain (greater than 1.5 x 10 exp 7) and background characteristics (about 0.5 events/sq cm per sec) of highly curved MCP stacks are in general equivalent to the performance achieved with flat MCP stacks of similar configuration. However, gain variations across the curved MCP's due to variations in the channel length to diameter ratio are observed. The overall pulse height distribution of a highly curved surface MCP stack (greater than 50 percent FWHM) is thus broader than its flat counterpart (less than 30 percent). Preconditioning of curved MCP stacks gives comparable results to flat MCP stacks, but it also decreases the overall gain variations. Flat fields of curved MCP stacks have the same general characteristics as flat MCP stacks.
Zhu, Hong-Ming; Pen, Ue-Li; Chen, Xuelei; Yu, Hao-Ran
2016-01-01
We present a direct approach to non-parametrically reconstruct the linear density field from an observed non-linear map. We solve for the unique displacement potential consistent with the non-linear density and positive definite coordinate transformation using a multigrid algorithm. We show that we recover the linear initial conditions up to $k\\sim 1\\ h/\\mathrm{Mpc}$ with minimal computational cost. This reconstruction approach generalizes the linear displacement theory to fully non-linear fields, potentially substantially expanding the BAO and RSD information content of dense large scale structure surveys, including for example SDSS main sample and 21cm intensity mapping.
Boyd, Robert W
2013-01-01
Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q
Probing exoplanet clouds with optical phase curves.
Muñoz, Antonio García; Isaak, Kate G
2015-11-01
Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve--from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the extent and location of the clouds. These considerations are relevant to the interpretation of optical phase curves with general circulation models. Finally, we estimate that the spherical albedo of Kepler-7b over the Kepler passband is in the range 0.4-0.5.
Improved Z-scan adjustment to thermal nonlinearities by including nonlinear absorption
Severiano-Carrillo, I.; Alvarado-Méndez, E.; Trejo-Durán, M.; Méndez-Otero, M. M.
2017-08-01
We propose a modified mathematical model of thermal optical nonlinearities which allow us to obtain the nonlinear refraction index and the nonlinear absorption coefficient with only one measurement. This modification is motivated by the influence that nonlinear absorption has on the measurement of the nonlinear refraction index at far field, when the material presents a large nonlinearity. This model, where nonlinear absorption is considered to adjust the curves of nonlinear refraction index obtained by Z-scan technique, has the best agreement with experimental data. The model is validated with two ionic liquids and the organic material Eysenhardtia polystachya, in thin media. We present these results after comparing our proposed model to other reported models.
Ruszczynski, Andrzej
2011-01-01
Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates t
Measurement of Temperature Change in Nonlinear Optical Materials by Using the Z-Scan Technique
Institute of Scientific and Technical Information of China (English)
DONG Shu-Guang; YANG Jun-Yi; SHUI Min; YI Chuan-Xiang; LI Zhong-Guo; SONG Ying-Lin
2011-01-01
@@ Spatial and temporal changes of temperature in a novel polymer are investigated by using the Z-scan technique under ns laser pulse excitation.According to the open aperture Z-scan experimental results, the nonlinear absorption coefficient of the polymer is determined.By solving the diffusion equation of heat conduction induced by optical absorption, the spatial and temporal changes in temperature are obtained.This change in temperature drives the photo-acoustic and electromagnetic wave propagating in the polymer and induces the change in refractive index, which serves as a negative lens, and the closed aperture Z-scan shows a peak and valley profile.Based on the numerical calculation, we achieve a good fit to the closed-aperture Z-scan curve with an optimized nonlinear refractive index.This consistency attests the existence of temperature change in the solution, and the Z-scan technique is suitable to investigate this change in temperature.
Chrastina, M.; Zejda, M.; Mikulášek, Z.
2010-12-01
The FITS standard allows arbitrary use of name-space for keywords, except some reserved keywords. Result of this freedom is that several keywords have the same meaning. Similar problem is that values of keywords have different physical units. These facts complicate automated data processing and also creation of FITS file archives with simple structure. MUNI-FITS-Utils is a package of Python scripts which have been developed in PyFITS, a Python FITS Module. Scripts are user-friendly and allow manipulating FITS headers to get uniform shape. Further functions will be added soon.
FIT3D: Fitting optical spectra
Sánchez, S. F.; Pérez, E.; Sánchez-Blázquez, P.; González, J. J.; Rosales-Ortega, F. F.; Cano-Díaz, M.; López-Cobá, C.; Marino, R. A.; Gil de Paz, A.; Mollá, M.; López-Sánchez, A. R.; Ascasibar, Y.; Barrera-Ballesteros, J.
2016-09-01
FIT3D fits optical spectra to deblend the underlying stellar population and the ionized gas, and extract physical information from each component. FIT3D is focused on the analysis of Integral Field Spectroscopy data, but is not restricted to it, and is the basis of Pipe3D, a pipeline used in the analysis of datasets like CALIFA, MaNGA, and SAMI. It can run iteratively or in an automatic way to derive the parameters of a large set of spectra.
Adaptive regression for modeling nonlinear relationships
Knafl, George J
2016-01-01
This book presents methods for investigating whether relationships are linear or nonlinear and for adaptively fitting appropriate models when they are nonlinear. Data analysts will learn how to incorporate nonlinearity in one or more predictor variables into regression models for different types of outcome variables. Such nonlinear dependence is often not considered in applied research, yet nonlinear relationships are common and so need to be addressed. A standard linear analysis can produce misleading conclusions, while a nonlinear analysis can provide novel insights into data, not otherwise possible. A variety of examples of the benefits of modeling nonlinear relationships are presented throughout the book. Methods are covered using what are called fractional polynomials based on real-valued power transformations of primary predictor variables combined with model selection based on likelihood cross-validation. The book covers how to formulate and conduct such adaptive fractional polynomial modeling in the s...
Approximation by planar elastic curves
DEFF Research Database (Denmark)
Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge
2016-01-01
We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient......-driven optimization is then used to find the approximating elastic curve....
Wang, Da-ming; Zhu, Bin; Ding, Liang-cai; Liu, Ning; Zhang, Jin-song
2010-06-01
To study the relationship between the resuscitation therapy and intensive insulin therapy on stress-induced hyperglycemia in severe sepsis and septic shock patients, and to evaluate the value on nonlinear viewpoint in the treatment of patients with sepsis. The data of 129 hospitalized patients with severe sepsis and septic shock were analyzed and they were divided into eight groups every 6 hours in ascending order for full recovery. The resuscitation therapy time of each group was compared with insulin dosage in each unit time with nonlinear least square method. The relationship of the exponential function fit very well between the resuscitation therapy time of each group and the insulin dosage in each unit time. The exponential curve equation was y=e0.739 3-0.015 2x2 (a=0.739 3, b=0.015 2) and the curve fit very well (R2=0.976 943 6). It conforms to the nonlinear viewpoint that the resuscitation therapy time is closely correlated with recovery of dysfunction of endocrine system during the treatment for patients with severe sepsis and septic shock. Therefore, the essence of successful treatment is to concentrate on helping the body rebuild the disorganized network and the recovery of physiological harmony rather than to support and repair the damaged organs.
Directory of Open Access Journals (Sweden)
M. Y. Conles
2011-06-01
Full Text Available En este trabajo se modela la curva de progreso de la podredumbre blanca en cultivos de ajo, mediante modelos no lineales mixtos que contemplan el efecto de factores concomitantes en el desarrollo de las epidemias. Entre 2001 y 2003 en Cruz del Eje y Jesús María, Argentina, se evaluaron la densidad inicial de esclerocios (DIE y la incidencia de la enfermedad quincenalmente hasta cosecha. Con DIE alta (>15 esclerocios/100 g de suelo la incidencia final fue alta (64-100% y con DIE baja (≤15 esclerocios/100 g de suelo varió entre 0-100%. El modelo logístico mixto seleccionado tuvo “interceptos” y pendientes aleatorias y diferentes para cada combinación de “ambiente” (localidad y año y categoría de DIE (altas y bajas. La representación de las curvas epidémicas se hizo mediante tres curvas específicas de sitio, la típica con efecto aleatorio cero, que expresa la forma general del modelo y las percentiles Q1 (0,25 y Q3 (0,75 que expresan la variabilidad. El 50% de las curvas tuvo pendientes entre r±0,67 v. La variabilidad de los “interceptos” y pendientes dependió solamente de la DIE, y fue menor en los “interceptos” con DIE “altas” que en aquellos con DIE “bajas”; en las pendientes se observó el efecto opuesto.This paper models the progress curve of white rot in garlic crops using nonlinear mixed models taking into account the effect of concomitant factors in the development of epidemics. Between 2001 and 2003 in Cruz del Eje and Jesus Maria, Argentina, the initial density of sclerotia (DIE and the incidence of the disease were evaluated every two weeks until harvest. With DIE high (>15 sclerotia/100 g of soil the final incidence was high (64-100%, while with DIE low (≤15 g soil sclerotia/100 the final incidence ranged from 0-100%. The mixed logistic model that was selected had random “intercepts” and rates which were different for each combination of “environment” (location and year and DIE category
Garrido, M; Larrechi, M S; Rius, F X
2006-02-01
This study describes the combination of multivariate curve resolution-alternating least squares with a kinetic modeling strategy for obtaining the kinetic rate constants of a curing reaction of epoxy resins. The reaction between phenyl glycidyl ether and aniline is monitored by near-infrared spectroscopy under isothermal conditions for several initial molar ratios of the reagents. The data for all experiments, arranged in a column-wise augmented data matrix, are analyzed using multivariate curve resolution-alternating least squares. The concentration profiles recovered are fitted to a chemical model proposed for the reaction. The selection of the kinetic model is assisted by the information contained in the recovered concentration profiles. The nonlinear fitting provides the kinetic rate constants. The optimized rate constants are in agreement with values reported in the literature.
Stankova-Frenkel, Z E
1997-01-01
We study the moduli of trigonal curves. We establish the exact upper bound of ${36(g+1)}/(5g+1)$ for the slope of trigonal fibrations. Here, the slope of any fibration $X\\to B$ of stable curves with smooth general member is the ratio Hodge class $\\lambda$ on the moduli space $\\bar{\\mathfrak{M}}_g$ to the base $B$. We associate to a trigonal family $X$ a canonical rank two vector bundle $V$, and show that for Bogomolov-semistable $V$ the slope satisfies the stronger inequality ${\\delta_B}/{\\lambda_B}\\leq 7+{6}/{g}$. We further describe the rational Picard group of the {trigonal} locus $\\bar{\\mathfrak T}_g$ in the moduli space $\\bar{\\mathfrak{M}}_g$ of genus $g$ curves. In the even genus case, we interpret the above Bogomolov semistability condition in terms of the so-called Maroni divisor in $\\bar{\\mathfrak T}_g$.
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Vesth, Allan
This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere......This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here......, the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...
Study on fitting methods for urban storm intensity formula%城市暴雨强度公式拟合方法研究
Institute of Scientific and Technical Information of China (English)
张子贤; 孙光东; 孙建印; 彭长刚
2013-01-01
Conventional method for determining the parameters of the storm intensity multi-period formula usually consists of two fitting processes,fitting the theory frequency curve and fitting the parameters of storm intensity multi-period formula. By such way to fit samples of the observed storm intensity, sum of squared error cannot reach the minimum. In this paper,a direct fitting method for storm intensity multi-pe-riod formula has been studied by nonlinear regression to directly fit the samples. With the storm intensity multi-period formula obtained by the direct fitting method,the minimum sum of squared error can be ac-quired in the process of fitting samples of observed storm intensity,and the best parameters are directly es-timated. Combined two examples, the direct fitting method were compared with the conventional methods by using different theory frequency curve. The results indicate that the direct fitting method is feasible, which can increase the fitting accuracy, decrease the processes of choosing and fitting for different theory frequen-cy curve,and avoid arbitrariness of deriving parameters for the storm intensity multi-period formula.%传统方法确定暴雨强度总公式的参数需要经过理论频率曲线拟合和总公式参数拟合两个环节，但由此法求得的暴雨强度总公式拟合实测雨强样本的误差平方和不为最小。本文采用非线性回归方法，研究了暴雨强度总公式直接拟合实测雨强样本的直接拟合法，使所求总公式拟合实测雨强样本的误差平方和为最小，实现了总公式参数的直接寻优。结合两个实例，对直接拟合法与采用不同理论频率分布的传统方法进行了比较，结果表明，直接拟合法切实可行，不仅使拟合精度提高，而且减少了不同理论频率曲线的选择与拟合环节，可避免推求暴雨强度总公式参数的任意性。
Grosse, Susan J.
2009-01-01
This article discusses how families can increase family togetherness and improve physical fitness. The author provides easy ways to implement family friendly activities for improving and maintaining physical health. These activities include: walking, backyard games, and fitness challenges.
Leslie, Mark; Holloway, Charles A
2006-01-01
When a company launches a new product into a new market, the temptation is to immediately ramp up sales force capacity to gain customers as quickly as possible. But hiring a full sales force too early just causes the firm to burn through cash and fail to meet revenue expectations. Before it can sell an innovative product efficiently, the entire organization needs to learn how customers will acquire and use it, a process the authors call the sales learning curve. The concept of a learning curve is well understood in manufacturing. Employees transfer knowledge and experience back and forth between the production line and purchasing, manufacturing, engineering, planning, and operations. The sales learning curve unfolds similarly through the give-and-take between the company--marketing, sales, product support, and product development--and its customers. As customers adopt the product, the firm modifies both the offering and the processes associated with making and selling it. Progress along the manufacturing curve is measured by tracking cost per unit: The more a firm learns about the manufacturing process, the more efficient it becomes, and the lower the unit cost goes. Progress along the sales learning curve is measured in an analogous way: The more a company learns about the sales process, the more efficient it becomes at selling, and the higher the sales yield. As the sales yield increases, the sales learning process unfolds in three distinct phases--initiation, transition, and execution. Each phase requires a different size--and kind--of sales force and represents a different stage in a company's production, marketing, and sales strategies. Adjusting those strategies as the firm progresses along the sales learning curve allows managers to plan resource allocation more accurately, set appropriate expectations, avoid disastrous cash shortfalls, and reduce both the time and money required to turn a profit.
Algebraic curves and cryptography
Murty, V Kumar
2010-01-01
It is by now a well-known paradigm that public-key cryptosystems can be built using finite Abelian groups and that algebraic geometry provides a supply of such groups through Abelian varieties over finite fields. Of special interest are the Abelian varieties that are Jacobians of algebraic curves. All of the articles in this volume are centered on the theme of point counting and explicit arithmetic on the Jacobians of curves over finite fields. The topics covered include Schoof's \\ell-adic point counting algorithm, the p-adic algorithms of Kedlaya and Denef-Vercauteren, explicit arithmetic on
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Villanueva, Héctor
This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here......, the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...
DEFF Research Database (Denmark)
Villanueva, Héctor; Vesth, Allan
are not performed according to IEC 61400-12-1 [1]. Therefore, the results presented in this report cannot be considered a power curve according to the reference standard, and are referred to as “power curve investigation” instead. The measurements have been performed by a customer and the data analysis has been......This report describes the analysis carried out with data from a given turbine in a wind farm and a chosen period. The purpose of the analysis is to correlate the power output of the wind turbine to the wind speed measured by a nacelle-mounted anemometer. The measurements and analysis...
Description of the growth curve for Angus pasture-fed cows under extensive systems.
Goldberg, V; Ravagnolo, O
2015-09-01
Growth curves are useful for describing the sigmoid shape of an animal's weight pattern over time. The purpose of the present study was to describe, for the first time, a complete growth curve for pasture-fed Angus cows in Uruguay and to analyze the major fixed effects that affect the estimation of mature cow weight (CW). A total of 22,743 records from 5,284 cows belonging to 73 herds were used in the statistical analysis. Five nonlinear models (Brody, Gompertz, Von Bertalanffy, logistic, and Richards) and a 3-knot cubic spline function were fitted to model weight change across age. Body weights were recorded at birth, weaning, and 18 mo and as an adult (at 2.3-3.6, 3.6-4.6, 4.6 to 5.6, 5.6 to 6.6, and 6.6 to 8.1 yr). After preliminary analyses, the fixed effects included in the model to estimate CW were BCS, herd, year and month of measurement, and age of dam. The herd and BCS were the major significant sources of variation. The Richards model had the lowest values for Akaike information criterion, Bayesian information criterion, and -2 log likelihood, with the asymptotic weight being 542 kg. The spline function was the model that fitted the data most closely to the observed weights followed by the Richards function. The Richards model gave better predictions of weights from birth to maturity than the other 4 nonlinear models, because these functions were shown to over- or underestimate weights at different ages in this beef cattle data set. The predicted curve showed that cows reach mature CW after 5 yr of age, which is the age commonly assumed as adult weight in beef cattle. Results form this analysis allowed the estimation of CW and rate of maturing and to take knowledge of the shape of growth curve for Angus females in Uruguay under extensive conditions, helping breeders to take selection decisions. In this way, breeders can optimize the management and efficiency for each production system.
THREE-DIMENSIONAL SLOPE STABILITY ANALYSIS BASED ON NONLINEAR FAILURE ENVELOPE%基于非线性破坏包络线的三维边坡稳定性分析
Institute of Scientific and Technical Information of China (English)
蒋景彩; 山上拓男; Baker R
2003-01-01
The effects of nonlinearity of strength envelopes on 3D slope stability analysis are investigated. A power relation for the nonlinear envelope is employed to derive the 3D factor of safety equations of an extended Spencer method which satisfies both force equilibrium and moment equilibrium. Then,a search procedure is presented based on dynamic programming to determine the 3D critical slip surface for a general slope. Linear and nonlinear strength envelopes used for slope stability computations are obtained by fitting curves to the 103 strength data of consolidated-undrained (CU) triaxial compression tests for compacted Israeli clay. Results of a typical 3D problem show that a linear approximation of the nonlinear strength envelope may lead to a significant overestimation of calculated safety factors.
NONLINEAR MODELS FOR DESCRIPTION OF CACAO FRUIT GROWTH WITH ASSUMPTION VIOLATIONS
Directory of Open Access Journals (Sweden)
JOEL AUGUSTO MUNIZ
2017-01-01
Full Text Available Cacao (Theobroma cacao L. is an important fruit in the Brazilian economy, which is mainly cultivated in the southern State of Bahia. The optimal stage for harvesting is a major factor for fruit quality and the knowledge on its growth curves can help, especially in identifying the ideal maturation stage for harvesting. Nonlinear regression models have been widely used for description of growth curves. However, several studies in this subject do not consider the residual analysis, the existence of a possible dependence between longitudinal observations, or the sample variance heterogeneity, compromising the modeling quality. The objective of this work was to compare the fit of nonlinear regression models, considering residual analysis and assumption violations, in the description of the cacao (clone Sial-105 fruit growth. The data evaluated were extracted from Brito and Silva (1983, who conducted the experiment in the Cacao Research Center, Ilheus, State of Bahia. The variables fruit length, diameter and volume as a function of fruit age were studied. The use of weighting and incorporation of residual dependencies was efficient, since the modeling became more consistent, improving the model fit. Considering the first-order autoregressive structure, when needed, leads to significant reduction in the residual standard deviation, making the estimates more reliable. The Logistic model was the most efficient for the description of the cacao fruit growth.
Institute of Scientific and Technical Information of China (English)
Joong-Hyun Rhim; Doo-Yeoun Cho; Kyu-Yeul Lee; Tae-Wan Kim
2006-01-01
We propose a method that automatically generates discrete bicubic G1 continuous B-spline surfaces that interpolate the curve network of a ship hullform. First, the curves in the network are classified into two types: boundary curves and "reference curves". The boundary curves correspond to a set of rectangular (or triangular) topological type that can be represented with tensor-product (or degenerate) B-spline surface patches. Next, in the interior of the patches,surface fitting points and cross boundary derivatives are estimated from the reference curves by constructing "virtual" isoparametric curves. Finally, a discrete G1 continuous B-spline surface is generated by a surface fitting algorithm. Several smooth ship hullform surfaces generated from curve networks corresponding to actual ship hullforms demonstrate the quality of the method.
Paths of algebraic hyperbolic curves
Institute of Scientific and Technical Information of China (English)
Ya-juan LI; Li-zheng LU; Guo-zhao WANG
2008-01-01
Cubic algebraic hyperbolic (AH) Bezier curves and AH spline curves are defined with a positive parameter α in the space spanned by {1, t, sinht, cosht}. Modifying the value of α yields a family of AH Bezier or spline curves with the family parameter α. For a fixed point on the original curve, it will move on a defined curve called "path of AH curve" (AH Bezier and AH spline curves) when α changes. We describe the geometric effects of the paths and give a method to specify a curve passing through a given point.
In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio
2012-12-01
The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Wagner, Rozenn
This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...
Kool, J.
2013-01-01
This thesis has three main subjects. The first subject is Measure-theoretic rigidity of Mumford Curves. One can describe isomorphism of two compact hyperbolic Riemann surfaces of the same genus by a measure-theoretic property: a chosen isomorphism of their fundamental groups corresponds to a homeomo
DEFF Research Database (Denmark)
Vesth, Allan; Kock, Carsten Weber
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present anal...
DEFF Research Database (Denmark)
Villanueva, Héctor; Gómez Arranz, Paula
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Villanueva, Héctor
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
Gompertz curves with seasonality
Ph.H.B.F. Franses (Philip Hans)
1994-01-01
textabstractThis paper considers an extension of the usual Gompertz curve by allowing the parameters to vary over the seasons. This means that, for example, saturation levels can be different over the year. An estimation and testing method is proposed and illustrated with an example.
DEFF Research Database (Denmark)
Gómez Arranz, Paula; Vesth, Allan
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
DEFF Research Database (Denmark)
Vesth, Allan; Yordanova, Ginka
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...
Lawes, Jonathan F.
2013-01-01
Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…
Power Curve Measurements, REWS
DEFF Research Database (Denmark)
Villanueva, Héctor; Gómez Arranz, Paula
This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere...
DEFF Research Database (Denmark)
Federici, Paolo; Kock, Carsten Weber
This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...
Straightening Out Learning Curves
Corlett, E. N.; Morecombe, V. J.
1970-01-01
The basic mathematical theory behind learning curves is explained, together with implications for clerical and industrial training, evaluation of skill development, and prediction of future performance. Brief studies of textile worker and typist training are presented to illustrate such concepts as the reduction fraction (a consistent decrease in…
Groot, L.F.M.
The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across
DEFF Research Database (Denmark)
Kock, Carsten Weber; Federici, Paolo
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....
DEFF Research Database (Denmark)
Kock, Carsten Weber; Vesth, Allan
The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....
Nonlinear acoustic propagation in two-dimensional ducts
Nayfeh, A. H.; Tsai, M.-S.
1974-01-01
The method of multiple scales is used to obtain a second-order uniformly valid expansion for the nonlinear acoustic wave propagation in a two-dimensional duct whose walls are treated with a nonlinear acoustic material. The wave propagation in the duct is characterized by the unsteady nonlinear Euler equations. The results show that nonlinear effects tend to flatten and broaden the absorption versus frequency curve, in qualitative agreement with the experimental observations. Moreover, the effect of the gas nonlinearity increases with increasing sound frequency, whereas the effect of the material nonlinearity decreases with increasing sound frequency.
Quantum fields in curved spacetime
Energy Technology Data Exchange (ETDEWEB)
Hollands, Stefan, E-mail: stefan.hollands@uni-leipzig.de [Universität Leipzig, Institut für Theoretische Physik, Brüderstrasse 16, D-04103 Leipzig (Germany); Wald, Robert M., E-mail: rmwa@uchicago.edu [Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, IL 60637 (United States)
2015-04-16
We review the theory of quantum fields propagating in an arbitrary, classical, globally hyperbolic spacetime. Our review emphasizes the conceptual issues arising in the formulation of the theory and presents known results in a mathematically precise way. Particular attention is paid to the distributional nature of quantum fields, to their local and covariant character, and to microlocal spectrum conditions satisfied by physically reasonable states. We review the Unruh and Hawking effects for free fields, as well as the behavior of free fields in deSitter spacetime and FLRW spacetimes with an exponential phase of expansion. We review how nonlinear observables of a free field, such as the stress–energy tensor, are defined, as well as time-ordered-products. The “renormalization ambiguities” involved in the definition of time-ordered products are fully characterized. Interacting fields are then perturbatively constructed. Our main focus is on the theory of a scalar field, but a brief discussion of gauge fields is included. We conclude with a brief discussion of a possible approach towards a nonperturbative formulation of quantum field theory in curved spacetime and some remarks on the formulation of quantum gravity.
Directory of Open Access Journals (Sweden)
Akemi Gálvez
2013-01-01
Full Text Available Fitting spline curves to data points is a very important issue in many applied fields. It is also challenging, because these curves typically depend on many continuous variables in a highly interrelated nonlinear way. In general, it is not possible to compute these parameters analytically, so the problem is formulated as a continuous nonlinear optimization problem, for which traditional optimization techniques usually fail. This paper presents a new bioinspired method to tackle this issue. In this method, optimization is performed through a combination of two techniques. Firstly, we apply the indirect approach to the knots, in which they are not initially the subject of optimization but precomputed with a coarse approximation scheme. Secondly, a powerful bioinspired metaheuristic technique, the firefly algorithm, is applied to optimization of data parameterization; then, the knot vector is refined by using De Boor’s method, thus yielding a better approximation to the optimal knot vector. This scheme converts the original nonlinear continuous optimization problem into a convex optimization problem, solved by singular value decomposition. Our method is applied to some illustrative real-world examples from the CAD/CAM field. Our experimental results show that the proposed scheme can solve the original continuous nonlinear optimization problem very efficiently.
Quasispecies on Fitness Landscapes.
Schuster, Peter
2016-01-01
Selection-mutation dynamics is studied as adaptation and neutral drift on abstract fitness landscapes. Various models of fitness landscapes are introduced and analyzed with respect to the stationary mutant distributions adopted by populations upon them. The concept of quasispecies is introduced, and the error threshold phenomenon is analyzed. Complex fitness landscapes with large scatter of fitness values are shown to sustain error thresholds. The phenomenological theory of the quasispecies introduced in 1971 by Eigen is compared to approximation-free numerical computations. The concept of strong quasispecies understood as mutant distributions, which are especially stable against changes in mutations rates, is presented. The role of fitness neutral genotypes in quasispecies is discussed.
Energy Technology Data Exchange (ETDEWEB)
Turchetti, G. (Bologna Univ. (Italy). Dipt. di Fisica)
1989-01-01
Research in nonlinear dynamics is rapidly expanding and its range of applications is extending beyond the traditional areas of science where it was first developed. Indeed while linear analysis and modelling, which has been very successful in mathematical physics and engineering, has become a mature science, many elementary phenomena of intrinsic nonlinear nature were recently experimentally detected and investigated, suggesting new theoretical work. Complex systems, as turbulent fluids, were known to be governed by intrinsically nonlinear laws since a long time ago, but received purely phenomenological descriptions. The pioneering works of Boltzmann and Poincare, probably because of their intrinsic difficulty, did not have a revolutionary impact at their time; it is only very recently that their message is reaching a significant number of mathematicians and physicists. Certainly the development of computers and computer graphics played an important role in developing geometric intuition of complex phenomena through simple numerical experiments, while a new mathematical framework to understand them was being developed.
Hu, Zeming; Chen, Xuechun; Wu, Yulin
The block-implicit finite-difference method is used to calculate 3D incompressible turbulent flows in the body-fitted coordinate system. In the numerical discretization the hybrid difference scheme is used to treat Reynolds-averaged Navier-Stokes equations. The iterative solution of velocities and pressure on the flow field is obtained by solving simultaneously the Reynolds-averaged N-S equations and continuity equation for each cell. In the iterative process the Gauss-Seidel method is used to solve nonlinear algebraic equations. The turbulent flow is simulated by the k-epsilon turbulence modeling in conjunction with Reynolds equations. The turbulent flow of a curved duct with square cross sections is treated in detail.
Probing exoplanet clouds with optical phase curves
Munoz, A Garcia
2015-01-01
Kepler-7b is to date the only exoplanet for which clouds have been inferred from the optical phase curve -- from visible-wavelength whole-disk brightness measurements as a function of orbital phase. Added to this, the fact that the phase curve appears dominated by reflected starlight makes this close-in giant planet a unique study case. Here we investigate the information on coverage and optical properties of the planet clouds contained in the measured phase curve. We generate cloud maps of Kepler-7b and use a multiple-scattering approach to create synthetic phase curves, thus connecting postulated clouds with measurements. We show that optical phase curves can help constrain the composition and size of the cloud particles. Indeed, model fitting for Kepler-7b requires poorly absorbing particles that scatter with low-to-moderate anisotropic efficiency, conclusions consistent with condensates of silicates, perovskite, and silica of submicron radii. We also show that we are limited in our ability to pin down the...
Influence of Nonlinear Absorption on Z-Scan Measurements of Nonlinear Refraction
Institute of Scientific and Technical Information of China (English)
刘智波; 田建国; 臧维平; 周文远; 张春平; 张光寅
2003-01-01
A simple division of close-aperture Z-scan curve by open-aperture Z-scan is conveniently used to obtain the nonlinear refractive index. It usually causes an error, which even reaches up to over 50% for Z-scan measurements with a pinhole or a medium with a high nonlinear absorption. Here the influence of nonlinear absorption on the determination of nonlinear refraction by Z-scan is analysed. We suggest that the error can be reduced greatly by a simple analysis of the symmetric features (symmetric method) of Z-scan curves from the closed-aperture Z-scan curve. As an example, experiments were carried out on CS2 solution of Ceo derivative, symmetric method agrees well with exact simulation.
Kruiver, Pauline P.; Dekkers, M.J.; Heslop, David
2002-01-01
A new method of analysing isothermal remanent magnetisation (IRM) acquisition curves based on cumulative log Gaussian analysis [Robertson and France, Phys. Earth Planet. Inter. 82 (1994) 223-234] is proposed. It is based on the curve fitting of the IRM acquisition curve versus the logarithm of the a
Energy Technology Data Exchange (ETDEWEB)
Groot, L. [Utrecht University, Utrecht School of Economics, Janskerkhof 12, 3512 BL Utrecht (Netherlands)
2008-11-15
The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across countries. These tools allow policy-makers and the general public to grasp at a single glance the impact of conventional distribution rules such as equal caps or grandfathering, or more sophisticated ones, on the distribution of greenhouse gas emissions. Second, using the Samuelson rule for the optimal provision of a public good, the Pareto-optimal distribution of carbon emissions is compared with the distribution that follows if countries follow Nash-Cournot abatement strategies. It is shown that the Pareto-optimal distribution under the Samuelson rule can be approximated by the equal cap division, represented by the diagonal in the Lorenz curve diagram.
Directory of Open Access Journals (Sweden)
Iram Ansari
2012-01-01
Full Text Available Dilaceration is the result of a developmental anomaly in which there has been an abrupt change in the axial inclination between the crown and the root of a tooth. Dilaceration can be seen in both the permanent and deciduous dentitions, and is more commonly found in posterior teeth and in maxilla. Periapical radiographs are the most appropriate way to diagnose the presence of root dilacerations. The controlled regularly tapered preparation of the curved canals is the ultimate challenge in endodontics. Careful and meticulous technique will yield a safe and sufficient enlargement of the curved canals. This article gives a review of the literature and three interesting case reports of root dilacerations.
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…
Nonlinear solar cycle forecasting: theory and perspectives
Directory of Open Access Journals (Sweden)
A. L. Baranovski
2008-02-01
Full Text Available In this paper we develop a modern approach to solar cycle forecasting, based on the mathematical theory of nonlinear dynamics. We start from the design of a static curve fitting model for the experimental yearly sunspot number series, over a time scale of 306 years, starting from year 1700 and we establish a least-squares optimal pulse shape of a solar cycle. The cycle-to-cycle evolution of the parameters of the cycle shape displays different patterns, such as a Gleissberg cycle and a strong anomaly in the cycle evolution during the Dalton minimum. In a second step, we extract a chaotic mapping for the successive values of one of the key model parameters – the rate of the exponential growth-decrease of the solar activity during the n-th cycle. We examine piece-wise linear techniques for the approximation of the derived mapping and we provide its probabilistic analysis: calculation of the invariant distribution and autocorrelation function. We find analytical relationships for the sunspot maxima and minima, as well as their occurrence times, as functions of chaotic values of the above parameter. Based on a Lyapunov spectrum analysis of the embedded mapping, we finally establish a horizon of predictability for the method, which allows us to give the most probable forecasting of the upcoming solar cycle 24, with an expected peak height of 93±21 occurring in 2011/2012.
Semiparametric analysis to estimate the deal effect curve
Van Heerde, HJ; Leeflang, PSH; Wittink, DR
2001-01-01
The marketing literature suggests several phenomena that may contribute to the nature of the relationship between sales and price discounts. These phenomena can produce complex nonlinearities and interactions in the deal effect curve that are best captured with a flexible approach. Because a fully n
Semiparametric analysis to estimate the deal effect curve
Heerde, Harald J. van; Leeflang, Peter S.H.; Wittink, Dick R.
1999-01-01
The marketing literature suggests several phenomena that may contribute to the shape of the relationship between sales and price discounts. These phenomena can produce severe nonlinearities and interactions in the curves, and we argue that those are best captured with a flexible approach. Since a fu
Vo, Martin
2017-08-01
Light Curves Classifier uses data mining and machine learning to obtain and classify desired objects. This task can be accomplished by attributes of light curves or any time series, including shapes, histograms, or variograms, or by other available information about the inspected objects, such as color indices, temperatures, and abundances. After specifying features which describe the objects to be searched, the software trains on a given training sample, and can then be used for unsupervised clustering for visualizing the natural separation of the sample. The package can be also used for automatic tuning parameters of used methods (for example, number of hidden neurons or binning ratio). Trained classifiers can be used for filtering outputs from astronomical databases or data stored locally. The Light Curve Classifier can also be used for simple downloading of light curves and all available information of queried stars. It natively can connect to OgleII, OgleIII, ASAS, CoRoT, Kepler, Catalina and MACHO, and new connectors or descriptors can be implemented. In addition to direct usage of the package and command line UI, the program can be used through a web interface. Users can create jobs for ”training” methods on given objects, querying databases and filtering outputs by trained filters. Preimplemented descriptors, classifier and connectors can be picked by simple clicks and their parameters can be tuned by giving ranges of these values. All combinations are then calculated and the best one is used for creating the filter. Natural separation of the data can be visualized by unsupervised clustering.
Pelce, Pierre
1989-01-01
In recent years, much progress has been made in the understanding of interface dynamics of various systems: hydrodynamics, crystal growth, chemical reactions, and combustion. Dynamics of Curved Fronts is an important contribution to this field and will be an indispensable reference work for researchers and graduate students in physics, applied mathematics, and chemical engineering. The book consist of a 100 page introduction by the editor and 33 seminal articles from various disciplines.
Estimating Corporate Yield Curves
Antionio Diaz; Frank Skinner
2001-01-01
This paper represents the first study of retail deposit spreads of UK financial institutions using stochastic interest rate modelling and the market comparable approach. By replicating quoted fixed deposit rates using the Black Derman and Toy (1990) stochastic interest rate model, we find that the spread between fixed and variable rates of interest can be modeled (and priced) using an interest rate swap analogy. We also find that we can estimate an individual bank deposit yield curve as a spr...
Steenwyk, Steven D; Molnar, Lawrence A
2013-01-01
We have identified some two-hundred new variable stars in a systematic study of a data archive obtained with the Calvin-Rehoboth observatory. Of these, we present five close binaries showing behaviors presumably due to star spots or other magnetic activity. For context, we first present two new RS CVn systems whose behavior can be readily attribute to star spots. Then we present three new close binary systems that are rather atypical, with light curves that are changing over time in ways not easily understood in terms of star spot activity generally associated with magnetically active binary systems called RS CVn systems. Two of these three are contact binaries that exhibit gradual changes in average brightness without noticeable changes in light curve shape. A third system has shown such large changes in light curve morphology that we speculate this may be a rare instance of a system that transitions back and forth between contact and noncontact configurations, perhaps driven by magnetic cycles in at least o...
Cooper, D. B.; Yalabik, N.
1975-01-01
Approximation of noisy data in the plane by straight lines or elliptic or single-branch hyperbolic curve segments arises in pattern recognition, data compaction, and other problems. The efficient search for and approximation of data by such curves were examined. Recursive least-squares linear curve-fitting was used, and ellipses and hyperbolas are parameterized as quadratic functions in x and y. The error minimized by the algorithm is interpreted, and central processing unit (CPU) times for estimating parameters for fitting straight lines and quadratic curves were determined and compared. CPU time for data search was also determined for the case of straight line fitting. Quadratic curve fitting is shown to require about six times as much CPU time as does straight line fitting, and curves relating CPU time and fitting error were determined for straight line fitting. Results are derived on early sequential determination of whether or not the underlying curve is a straight line.
DEFF Research Database (Denmark)
Schmeltz, Line
2017-01-01
Companies experience increasing legal and societal pressure to communicate about their corporate social responsibility (CSR) engagements from a number of different publics. One very important group is that of young consumers who are predicted to be the most important and influential consumer group...... in the near future. From a value- theoretical base, this article empirically explores the role and applicability of ‘fit’ in strategic CSR communication targeted at young consumers. Point of departure is taken in the well-known strategic fit (a logical link between a company’s CSR commitment and its core...... values) and is further developed by introducing two additional fits, the CSR- Consumer fit and the CSR-Consumer-Company fit (Triple Fit). Through a sequential design, the three fits are empirically tested and their potential for meeting young consumers’ expectations for corporate CSR messaging...
2015-09-01
Fill cannot. NEC Fit NEC Fit measures more than the crew’s total skill sets. It also accounts for how these sailors are used by crediting an NEC...Abstract Navy enlisted classifications (NECs) denote special skills beyond those associated with a rating. They are used in defining manpower...requirements and in managing personnel by tracking sailors who have acquired these skills . NEC Fit is one of two primary metrics that Navy leadership
Galaxy rotation curves with log-normal density distribution
Marr, John H
2015-01-01
The log-normal distribution represents the probability of finding randomly distributed particles in a micro canonical ensemble with high entropy. To a first approximation, a modified form of this distribution with a truncated termination may represent an isolated galactic disk, and this disk density distribution model was therefore run to give the best fit to the observational rotation curves for 37 representative galaxies. The resultant curves closely matched the observational data for a wide range of velocity profiles and galaxy types with rising, flat or descending curves in agreement with Verheijen's classification of 'R', 'F' and 'D' type curves, and the corresponding theoretical total disk masses could be fitted to a baryonic Tully Fisher relation (bTFR). Nine of the galaxies were matched to galaxies with previously published masses, suggesting a mean excess dynamic disk mass of dex0.61+/-0.26 over the baryonic masses. Although questionable with regard to other measurements of the shape of disk galaxy g...
Dose-response curve estimation: a semiparametric mixture approach.
Yuan, Ying; Yin, Guosheng
2011-12-01
In the estimation of a dose-response curve, parametric models are straightforward and efficient but subject to model misspecifications; nonparametric methods are robust but less efficient. As a compromise, we propose a semiparametric approach that combines the advantages of parametric and nonparametric curve estimates. In a mixture form, our estimator takes a weighted average of the parametric and nonparametric curve estimates, in which a higher weight is assigned to the estimate with a better model fit. When the parametric model assumption holds, the semiparametric curve estimate converges to the parametric estimate and thus achieves high efficiency; when the parametric model is misspecified, the semiparametric estimate converges to the nonparametric estimate and remains consistent. We also consider an adaptive weighting scheme to allow the weight to vary according to the local fit of the models. We conduct extensive simulation studies to investigate the performance of the proposed methods and illustrate them with two real examples.
Degroote, P; Catala, C; Uytterhoeven, K; Lefever, K; Morel, T; Aerts, C; Carrier, F; Auvergne, M; Baglin, A; Michel, E
2009-01-01
We present the CoRoT light curve of the Beta Cep star HD 180642, assembled during the first long run of the space mission, as well as archival single-band photometry. Our goal is to analyse the detailed behaviour present in the light curve and interpret it in terms of excited mode frequencies. After describing the noise properties in detail, we use various time series analysis and fitting techniques to model the CoRoT light curve, for various physical assumptions. We apply statistical goodness-of-fit criteria that allow us to select the most appropriate physical model fit to the data. We conclude that the light curve model based on nonlinear resonant frequency and phase locking provides the best representation of the data. The interpretation of the residuals is dependent on the chosen physical model used to prewhiten the data. Our observational results constitute a fruitful starting point for detailed seismic stellar modelling of this large-amplitude and evolved Beta Cep star.
Non-linear structural dynamics characterization using a scanning laser vibrometer
Pai, P. F.; Lee, S.-Y.
2003-07-01
This paper presents the use of a scanning laser vibrometer and a signal decomposition method to characterize non-linear dynamics of highly flexible structures. A Polytec PI PSV-200 scanning laser vibrometer is used to measure transverse velocities of points on a structure subjected to a harmonic excitation. Velocity profiles at different times are constructed using the measured velocities, and then each velocity profile is decomposed using the first four linear mode shapes and a least-squares curve-fitting method. From the variations of the obtained modal velocities with time we search for possible non-linear phenomena. A cantilevered titanium alloy beam subjected to harmonic base-excitations around the second, third, and fourth natural frequencies are examined in detail. Influences of the fixture mass, gravity, mass centers of mode shapes, and non-linearities are evaluated. Geometrically exact equations governing the planar, harmonic large-amplitude vibrations of beams are solved for operational deflection shapes using the multiple shooting method. Experimental results show the existence of 1:3 and 1:2:3 external and internal resonances, energy transfer from high-frequency modes to the first mode, and amplitude- and phase-modulation among several modes. Moreover, the existence of non-linear normal modes is found to be questionable.
FORCED OSCILLATIONS IN NONLINEAR FEEDBACK CONTROL SYSTEM
Since a nonlinear feedback control system may possess more than one type of forced oscillations, it is highly desirable to investigate the type of...method for finding the existence of forced oscillations and response curve characteristics of a nonlinear feedback control system by means of finding the...second order feedback control system are investigated; the fundamental frequency forced oscillation for a higher order system and the jump resonance
Theory of nonlinear elastic behavior in rock
Energy Technology Data Exchange (ETDEWEB)
McCall, K.R.
1993-04-01
We study plane wave propagation in an isotropic, homogeneous solid with cubic and quartic anharmonicity. Attenuation is introduced through use of a retarded displacement response. We develop a Green function technique to exhibit the solution for the displacement field as a systematic hierarchy in the nonlinear parameters. This solution is applied to three problems: propagation from monochromatic and broadband sources, and the shape of nonlinear stress curves.
Theory of nonlinear elastic behavior in rock
Energy Technology Data Exchange (ETDEWEB)
McCall, K.R.
1993-01-01
We study plane wave propagation in an isotropic, homogeneous solid with cubic and quartic anharmonicity. Attenuation is introduced through use of a retarded displacement response. We develop a Green function technique to exhibit the solution for the displacement field as a systematic hierarchy in the nonlinear parameters. This solution is applied to three problems: propagation from monochromatic and broadband sources, and the shape of nonlinear stress curves.
Curved PVDF airborne transducer.
Wang, H; Toda, M
1999-01-01
In the application of airborne ultrasonic ranging measurement, a partially cylindrical (curved) PVDF transducer can effectively couple ultrasound into the air and generate strong sound pressure. Because of its geometrical features, the ultrasound beam angles of a curved PVDF transducer can be unsymmetrical (i.e., broad horizontally and narrow vertically). This feature is desired in some applications. In this work, a curved PVDF air transducer is investigated both theoretically and experimentally. Two resonances were observed in this transducer. They are length extensional mode and flexural bending mode. Surface vibration profiles of these two modes were measured by a laser vibrometer. It was found from the experiment that the surface vibration was not uniform along the curvature direction for both vibration modes. Theoretical calculations based on a model developed in this work confirmed the experimental results. Two displacement peaks were found in the piezoelectric active direction of PVDF film for the length extensional mode; three peaks were found for the flexural bending mode. The observed peak positions were in good agreement with the calculation results. Transient surface displacement measurements revealed that vibration peaks were in phase for the length extensional mode and out of phase for the flexural bending mode. Therefore, the length extensional mode can generate a stronger ultrasound wave than the flexural bending mode. The resonance frequencies and vibration amplitudes of the two modes strongly depend on the structure parameters as well as the material properties. For the transducer design, the theoretical model developed in this work can be used to optimize the ultrasound performance.
Magnetism in curved geometries
Streubel, Robert; Fischer, Peter; Kronast, Florian; Kravchuk, Volodymyr P.; Sheka, Denis D.; Gaididei, Yuri; Schmidt, Oliver G.; Makarov, Denys
2016-09-01
Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii-Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.
On the prediction of stress relaxation from known creep of nonlinear materials
Energy Technology Data Exchange (ETDEWEB)
Touati, D.; Cederbaum, G. [Ben-Gurion Univ. of the Negev, Beer Sheva (Israel)
1997-04-01
A method to predict the nonlinear relaxation behavior from creep experiments of nonlinear viscoelastic materials is presented. It is shown that for given nonlinear creep properties, and creep compliance represented by the Prony series, the Schapery creep model can be transformed into a set of first order nonlinear equations. The solution of these equations enables the obtaining of the nonlinear stress relaxation curves. The strain-dependent constitutive equation can then be constructed for a given nonlinear viscoelastic model, as needed for engineering applications. A comparison example of the calculated stress relaxation curves, with test data for polyurethane demonstrates the very good accuracy of the proposed method.
Computer program for fitting low-order polynomial splines by method of least squares
Smith, P. J.
1972-01-01
FITLOS is computer program which implements new curve fitting technique. Main program reads input data, calls appropriate subroutines for curve fitting, calculates statistical analysis, and writes output data. Method was devised as result of need to suppress noise in calibration of multiplier phototube capacitors.
Contrast Gain Control Model Fits Masking Data
Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)
1994-01-01
We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.
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...
DEFF Research Database (Denmark)
Giardino, P. P.; Kannike, K.; Masina, I.
2014-01-01
Higgs models, models with extra Higgs doublets, supersymmetry, extra particles in the loops, anomalous top couplings, and invisible Higgs decays into Dark Matter. Best fit regions lie around the Standard Model predictions and are well approximated by our 'universal' fit. Latest data exclude the dilaton...
Maiorano, Joseph J.
2001-01-01
Fit 2-B FATHERS is a parenting-skills education program for incarcerated adult males. The goals of this program are for participants to have reduced recidivism rates and a reduced risk of their children acquiring criminal records. These goals are accomplished by helping participants become physically, practically, and socially fit for the demands…
2004-01-01
The mineralogy of 'Bounce' rock was determined by fitting spectra from a library of laboratory minerals to the spectrum of Bounce taken by the Mars Exploration Rover Opportunity's miniature thermal emission spectrometer. The minerals that give the best fit include pyroxene, plagioclase and olivine -- minerals commonly found in basaltic volcanic rocks -- and typical martian dust produced by the rover's rock abrasion tool.
Institute of Scientific and Technical Information of China (English)
Karen; Clark
2005-01-01
Summer is a time to exercise and keep fit.Ask yourself these quick questions and check your score below.How fit are you? 1.What is your pulse[脉搏]?Find your pulse in your wrist[手腕], count the number of beats[跳动] in one minute,Now
Vertiz, Virginia C.; Downey, Carolyn J.
This paper proposes a two-pronged approach for examining an educational program's "quality of fit." The American Association of School Administrators' (AASA's) Curriculum Management Audit for quality indicators is reviewed, using the Downey Quality Fit Framework and Deming's 4 areas of profound knowledge and 14 points. The purpose is to…
Probing hysteretic elasticity in weakly nonlinear materials
Energy Technology Data Exchange (ETDEWEB)
Johnson, Paul A [Los Alamos National Laboratory; Haupert, Sylvain [UPMC UNIV PARIS; Renaud, Guillaume [UPMC UNIV PARIS; Riviere, Jacques [UPMC UNIV PARIS; Talmant, Maryline [UPMC UNIV PARIS; Laugier, Pascal [UPMC UNIV PARIS
2010-12-07
Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.
Curve Number estimation from rainfall-runoff data in the Brazilian Cerrado Biome
Oliveira, P. S.; Nearing, M.; Rodrigues, D. B.; Panachuki, E.; Wendland, E.
2013-12-01
The Brazilian Cerrado (Savanna) is considered one of the most important biomes for Brazilian water resources; meanwhile, it is experiencing major losses of its natural landscapes due to the pressures of food and energy production, which has caused changes in hydrological processes. To evaluate these changes hydrologic models have been used. The Curve Number (SCS-CN) method has been widely employed to estimate direct runoff from a given rainfall event, however, there are some uncertainties for estimating this parameter, particularly for use in areas with native vegetation. The objectives of this study were to measure natural rainfall-driven rates of runoff under native Cerrado vegetation and under the main crops found in this biome, and derive associated CN values from five methods. We used six plots of 5 x 20 m (100 m2) in size, with three replications of undisturbed Cerrado and three under bare soil (Ortic Quartzarenic Neosol, hydrological soil class A) and 10 plots of 3.5 x 22.15 m (77.5 m2), with two replications for pasture, soy, millet, sugarcane and bare soil (Dystrophic Red Argisol, hydrological soil class B). Plots were monitored between October 2011 and April 2013. The five methods used to obtain CN values were median, geometric mean, arithmetic mean, nonlinear, least squares fit, and standard asymptotic fit. We found reasonable results for CN calibration for the undisturbed Cerrado only by using the nonlinear least squares fit. CN obtained from the standard table values was not adequate to estimate runoff for this condition. The standard table and the five CN methods presented satisfactory results for the other land covers studied. From our results we can suggest the best CN values for each land cover: Cerrado 49.8 (47.9-51.1), bare soil class-A 83.9 (74.4-93.4), bare soil class-B 88.3 (81.7-94.8), pasture 73.7 (62.9-84.5), soy 83.5 (80.6-86.4), millet 73.9 (67.4-80.4) and sugarcane 83.9 (80.6-87.3). These CN values and ranges provide guidance for
Minimax hypothesis testing for curve registration
Collier, Olivier
2011-01-01
This paper is concerned with the problem of goodness-of-fit for curve registration, and more precisely for the shifted curve model, whose application field reaches from computer vision and road traffic prediction to medicine. We give bounds for the asymptotic minimax separation rate, when the functions in the alternative lie in Sobolev balls and the separation from the null hypothesis is measured by the l2-norm. We use the generalized likelihood ratio to build a nonadaptive procedure depending on a tuning parameter, which we choose in an optimal way according to the smoothness of the ambient space. Then, a Bonferroni procedure is applied to give an adaptive test over a range of Sobolev balls. Both achieve the asymptotic minimax separation rates, up to possible logarithmic factors.
Light extraction block with curved surface
Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.
2016-03-22
Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.
Nonlinear and Stochastic Morphological Segregation
Blanton, M R
1999-01-01
I perform a joint counts-in-cells analysis of galaxies of different spectral types using the Las Campanas Redshift Survey (LCRS). Using a maximum-likelihood technique to fit for the relationship between the density fields of early- and late-type galaxies, I find a relative linear bias of $b=0.76\\pm 0.02$. This technique can probe the nonlinearity and stochasticity of the relationship as well. However, the degree to which nonlinear and stochastic fits improve upon the linear fit turns out to depend on the redshift range in question. In particular, there seems to be a systematic difference between the high- and low-redshift halves of the data (respectively, further than and closer than $cz\\approx 36,000$ km/s); all of the signal of stochasticity and nonlinearity comes from the low-redshift portion. Analysis of mock catalogs shows that the peculiar geometry and variable flux limits of the LCRS do not cause this effect. I speculate that the central surface brightness selection criteria of the LCRS may be responsi...
Bayat, Hossein; Sedaghat, Azadeh; Safari Sinegani, Ali Akbar; Gregory, Andrew S.
2015-03-01
This study was conducted to estimate the soil unsaturated hydraulic conductivity through the van Genuchten model using easy to measure soil properties by regression and artificial neural networks methods. In this study, 148 soil samples were taken from five provinces of Iran. Basic soil properties (clay, silt/sand and bulk density) and other soil properties were measured. Soil water retention curve was measured to obtain the unsaturated hydraulic conductivity curve using the van Genuchten-Mualem model. Confined compression curve was measured and the modified model of van Genuchten was fitted on its data. Two-thirds and one-third of the data were used for the training and testing steps, respectively. Confined compression curve parameters and other soil properties were used as predictors to estimate unsaturated hydraulic conductivity curve. Pedotransfer functions (PTFs) were developed in two separate parts: in 5 and 6 PTFs basic soil properties were or were not used as predictors, respectively. The artificial neural networks (ANNs) performed better than the regression methods. Among the ANN-developed PTFs which have not used basic soil properties as predictors, PTFa3, with the inputs of the parameters of confined compression curve (n∗, α∗ and e0), performed better than the others. Also, among the ANN-developed PTFs that used basic soil properties as predictors along with the other input variables, PTFb5 that used the σmc (stress at the maximum curvature) and σi (stress at the inflection point) as inputs along with basic soil properties, performed better than the other PTFs. The results showed a successful prediction of the hydraulic conductivity curve using confined compression curve.
Nonlinear Particle Acceleration and Thermal Particles in GRB Afterglows
Warren, Donald C.; Ellison, Donald C.; Barkov, Maxim V.; Nagataki, Shigehiro
2017-02-01
The standard model for GRB afterglow emission treats the accelerated electron population as a simple power law, N(E)\\propto {E}-p for p≳ 2. However, in standard Fermi shock acceleration, a substantial fraction of the swept-up particles do not enter the acceleration process at all. Additionally, if acceleration is efficient, then the nonlinear back-reaction of accelerated particles on the shock structure modifies the shape of the nonthermal tail of the particle spectra. Both of these modifications to the standard synchrotron afterglow impact the luminosity, spectra, and temporal variation of the afterglow. To examine the effects of including thermal particles and nonlinear particle acceleration on afterglow emission, we follow a hydrodynamical model for an afterglow jet and simulate acceleration at numerous points during the evolution. When thermal particles are included, we find that the electron population is at no time well fitted by a single power law, though the highest-energy electrons are; if the acceleration is efficient, then the power-law region is even smaller. Our model predicts hard–soft–hard spectral evolution at X-ray energies, as well as an uncoupled X-ray and optical light curve. Additionally, we show that including emission from thermal particles has drastic effects (increases by factors of 100 and 30, respectively) on the observed flux at optical and GeV energies. This enhancement of GeV emission makes afterglow detections by future γ-ray observatories, such as CTA, very likely.
Properties of analytic transit light curve models
Pál, András
2008-01-01
In this paper a set of analytic formulae are presented with which the partial derivatives of the flux obscuration function can be evaluated -- for planetary transits and eclipsing binaries -- under the assumption of quadratic limb darkening. The knowledge of these partial derivatives are crucial for many of the data modeling algorithms and estimates of the light curve variations directly from the changes in the orbital elements. These derivatives can also be utilized to speed up some of the fitting methods. A gain of 10 in computing time can be achieved in the implementation of the Levenberg-Marquardt algorithm, relative to using numerical derivatives.
Nonlinear Finite Element Analysis of Ocean Cables
Institute of Scientific and Technical Information of China (English)
Nam-Il KIM; Sang-Soo JEON; Moon-Young KIM
2004-01-01
This study has focused on developing numerical procedures for the dynamic nonlinear analysis of cable structures subjected to wave forces and ground motions in the ocean. A geometrically nonlinear finite element procedure using the isoparametric curved cable element based on the Lagrangian formulation is briefly summarized. A simple and accurate method to determine the initial equilibrium state of cable systems associated with self-weights, buoyancy and the motion of end points is presented using the load incremental method combined with penalty method. Also the Newmark method is used for dynamic nonlinear analysis of ocean cables. Numerical examples are presented to validate the present numerical method.
Moving non-null curves according to Bishop frame in Minkowski 3-space
Gürbüz, Nevin
2015-04-01
In this paper, we introduce three new transformations and establish connections between moving non-null curves and soliton equations according to Bishop frame in Minkowski 3-space. Later we find formulas for differentials of these three new transformations associated with the nonlinear heat system and repulsive type nonlinear Schrödinger equation.
Energy Technology Data Exchange (ETDEWEB)
Molli, Muralikrishna, E-mail: muralikrishnamolli@sssihl.edu.in [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthinilayam-515 134 (India); Parola, Sowmendran; Avinash Chunduri, L.A.; Aditha, Saikiran; Sai Muthukumar, V; Mimani Rattan, Tanu; Kamisetti, Venkataramaniah [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthinilayam-515 134 (India)
2012-05-15
Nanocrystalline Bismuth telluride and thallium (4 mol %) doped Bismuth telluride were synthesized through hydrothermal method. The as-prepared products were characterized using Powder X-ray Diffraction, High Resolution Transmission Electron Microscopy, Energy Dispersive X-Ray Spectroscopy, UV-Visible spectroscopy and Fourier Transform Infrared Spectroscopy. Powder XRD results revealed the crystalline nature of the obtained phases. HRTEM showed the particle-like morphology of the products. The decrease in the absorption coefficient due to thallium doping was observed in FTIR spectra. The intensity dependent nonlinear optical properties of nanocrystalline bismuth telluride and thallium doped bismuth telluride were studied using the Z-scan technique in open-aperture configuration. Bismuth telluride doped with thallium showed enhanced nonlinear optical response compared to pristine bismuth telluride and hence could be used as a potential candidate for optical power limiting applications. - Graphical Abstract: Nonlinear transmission (Z-scan) curves of nanocrystalline bismuth telluride ({Delta}) and thallium doped bismuth telluride ({open_square}). Thallium doped bismuth telluride showed enhanced nonlinear absorption compared to bismuth telluride. Inset: TEM micrograph of bismuth telluride nanocrystallites. Highlights: Black-Right-Pointing-Pointer Synthesis of Nanocrystalline Bi{sub 2}Te{sub 3} and Thallium doped Bi{sub 2}Te{sub 3} through solvothermal method. Black-Right-Pointing-Pointer Reduced absorption coefficient due to thallium doping found from IR spectroscopy. Black-Right-Pointing-Pointer Open-aperture Z-scan technique for nonlinear optical studies. Black-Right-Pointing-Pointer Two photon absorption based model for theoretical fitting of Z-scan data. Black-Right-Pointing-Pointer Enhanced nonlinear absorption in Thallium doped Bi{sub 2}Te{sub 3} - potential candidate for optical power limiting applications.