A multivariate modeling technology is developed that allows engineers to define the frequency range, layout parameters, material properties and desired accuracy for automatic generation of simulation models of general...
详细信息
ISBN:
(纸本)0972842217
A multivariate modeling technology is developed that allows engineers to define the frequency range, layout parameters, material properties and desired accuracy for automatic generation of simulation models of general passive electrical structures. It combines electromagnetic (EM) accuracy of parameterized passive models with the simulation speed of analytical models. The adaptive algorithm doesn't require any a priori knowledge of the dynamics of the system to select an appropriate sample distribution and an appropriate model complexity. With this technology, designers no longer must put up with legacy modeling techniques or invest resources in examining new ones.
Online optimization is more and more used in the chemical industry to run a process near its Optimum operating condition by providing real-time computed optimal set-points to the distributed control system. Process me...
详细信息
Online optimization is more and more used in the chemical industry to run a process near its Optimum operating condition by providing real-time computed optimal set-points to the distributed control system. Process measurements are necessary for these applications to determine the actual state of the process and to increase the accuracy of the model with parameterestimation techniques. However, these measurements usually contain random as well as gross errors which have to be identified and eliminated before the measurements are used for online optimization. In this contribution. a data reconciliation approach was integrated into an online optimization framework for the ammonia hydrogen sulfide circulation scrubbing, a common industrial coke-oven-gas purification process. We used a rigorous rate-basedmodel to describe this reactive absorption and desorption process. To increase the accuracy of the model, we estimated several process parameters using a sequential parameterestimation approach. Data reconciliation was performed based on simple component balances to achieve model-consistent data and to identify measurement biases. The model was then validated online on a pilot plant by connecting the estimation package through the process control system. based on the online measured data, operating cost minimization was carried out and the computed optimal set-points realized real-time. A satisfactory agreement between measured data and optimization was achieved. (c) 2006 Elsevier B.V. All rights reserved.
To improve the prediction of the osteoporotic fracture risk at the proximal femur we are developing a scanner for Quantitative Ultrasound (QUS) measurements at this site. Due to multipath transmission in this complex ...
详细信息
ISBN:
(纸本)9781424402014
To improve the prediction of the osteoporotic fracture risk at the proximal femur we are developing a scanner for Quantitative Ultrasound (QUS) measurements at this site. Due to multipath transmission in this complex shaped bone conventional signal processing techniques developed for QUS measurements at peripheral sites frequently fail. Applying a model-basedestimation method to Quantitative Ultrasound scans of excised proximal femurs the fraction of evaluable signals can be increased from approx. 60% (using conventional algorithms) to 95%. The correlation of the standard QUS variables Broadband Ultrasound Attenuation (BUA) and Speed-of-Sound (SOS) with the established variable Bone Mineral Density (BMD) reported in previous studies is maintained (r(BUA/BMD)(2) = 0.69, r(SOS/BMD)(2) = 0.82). Because of its ability to separate superimposed signals this approach opens up further diagnostic potential by evaluating the information of waves of different sound paths through the bone.
An ultra-compact metallic photonic crystal filter for telecommunication wavelength is designed using the Multiple Multipole Program combined with the model-based parameter estimation technique. Material loss is taken ...
详细信息
ISBN:
(纸本)078039433X
An ultra-compact metallic photonic crystal filter for telecommunication wavelength is designed using the Multiple Multipole Program combined with the model-based parameter estimation technique. Material loss is taken into account and measured data is employed to make this,design more realistic. Finally, deterministic optimization techniques are applied for obtaining the desired filter characteristics.
The Pade rational function fitting model commonly used for model-based parameter estimation (MBPE) in the frequency domain is enhanced to include spatial dependence in the numerator and denominator coefficients. This ...
详细信息
The Pade rational function fitting model commonly used for model-based parameter estimation (MBPE) in the frequency domain is enhanced to include spatial dependence in the numerator and denominator coefficients. This allow's the function to interpolate an antenna radiated electric field pattern in both the frequency and spatial domains simultaneously, such that a single set of coefficients ran be used to accurately reconstruct an entire radiation pattern at any frequency in the fitting-model range. A simple procedure is introduced for transforming interpolated electric fields into gain patterns using input impedance versus frequency curves also obtained via MBPE. The utility of this method is demonstrated by applying it to a dipole antenna over a frequency range of 150-950 MHz and using a polynomial representation in theta for the coefficient spatial dependence. It is also used to estimate radiation patterns for a three-element Yagi array between the frequencies of 470 and 500 MHz using a binomial representation for the spatial variation that includes terms dependent on theta as well as phi. The use of this method for interpolating radiation patterns has at least two significant advantages;one being large compression ratios for the amount of data that must be stored to accurately reproduce patterns and the other being a significant decrease in the amount of time required for modeling problems with large computational domains.
An efficient numerical method is proposed and implemented for the analysis of propagation characteristics of single-mode optical fibers with arbitrary refractive index profile. The method follows the concept of the so...
详细信息
An efficient numerical method is proposed and implemented for the analysis of propagation characteristics of single-mode optical fibers with arbitrary refractive index profile. The method follows the concept of the so-called model-based parameter estimation, and the Pade algorithm is used to construct a low-order rational approximant of the spectral domain Green's function, obtained by solving a hierarchy of static problems, The sought eigenfrequency and held distribution are then estimated by computing, respectively, the dominant pole and the related residual of the rational approximant. A number of profiles are analyzed and experiments show that very accurate results can be cheaply obtained through this technique.
A fast and efficient adaptive sampling algorithm for multivariate, multiple output rational interpolation models is presented, which is based on convergents of Thiele type branched continued fractions. The multiple ou...
详细信息
A fast and efficient adaptive sampling algorithm for multivariate, multiple output rational interpolation models is presented, which is based on convergents of Thiele type branched continued fractions. The multiple output interpolation model consists of a set of rational interpolants, and each interpolant models one of the output parameters. A single global error function is defined that incorporates all the output parameters, and it is used for the selection of the same set of support points for all the interpolants. The technique is evaluated on several passive microwave structures and compared to previously published results. (C) 2002 Wiley Periodicals, Inc.
A fast and efficient adaptive sampling algorithm for multivariate rational interpolation models based on convergents of Thiele-type branched continued fractions (BCFs) is presented in this paper. We propose a variatio...
详细信息
A fast and efficient adaptive sampling algorithm for multivariate rational interpolation models based on convergents of Thiele-type branched continued fractions (BCFs) is presented in this paper. We propose a variation of the standard BCF that uses approximation to establish a nonrectangular grid of support points. Starting with a low-order interpolant, the technique systematically increases the order by optimally choosing new support points in the areas of highest error until the required accuracy is achieved. In this way, accurate surrogate models are established by a small number of support points without any a priori knowledge of the data. The technique is evaluated on several passive microwave structures.
暂无评论