Showing papers on "Analytical technique published in 2005"
14 Jan 2005
462 citations
TL;DR: The unified mathematical approach presented below is a synthesis technique founded on the mathematical transformation of the desired field pattern, followed by the application of limiting forms of the transformation, and resulting in the development of a closed form expression for the element positions.
Abstract: An effective method for optimizing the performance of a fixed current distribution, uniformly spaced antenna array has been to adjust its element positions to provide performance improvement. In comparison with the default uniform structure, this approach yields performance improvements such as smaller sidelobe levels or beamwidth values. Additionally, it provides practical advantages such as reductions in size, weight and number of antenna elements. The objective of this paper is to describe a unified mathematical approach to nonlinear optimization of multidimensional array geometries. The approach utilizes a class of limiting properties of sinusoidal, Bessel or Legendre functions that are dictated by the array geometry addressed. The efficacy of the method is demonstrated by its generalized application to synthesis of rectangular, cylindrical and spherical arrays. The unified mathematical approach presented below is a synthesis technique founded on the mathematical transformation of the desired field pattern, followed by the application of limiting forms of the transformation, and resulting in the development of a closed form expression for the element positions. The method offers the following advantages over previous techniques such as direct nonlinear optimization or genetic algorithms. First, it is not an iterative, searching algorithm, and provides element spacing values directly in a single run of the algorithm, thereby saving valuable CPU time and memory storage. Second, It permits the array designer to place practical constraints on the array geometry, (e.g., the minimum/maximum spacing between adjacent elements)
179 citations
24 Oct 2005
TL;DR: Comparisons between analytical, finite element analysis (FEA), and experimental results are presented that confirm the ability of fractional-slot concentrated winding SPM machines to achieve their high-speed operating objectives.
Abstract: Previous analytical work has shown that it is possible to design surface permanent-magnet (SPM) machines using fractional-slot concentrated windings to achieve wide speed ranges of constant power operation by satisfying the optimal flux-weakening condition. This paper presents a 6-kW 36-slot/30-pole concentrated winding prototype SPM machine that has been designed using a closed-form analytical technique developed specifically for this class of machines. Experimental testing of this machine has been carried out to determine its performance capabilities, including flux-weakening operation. Detailed comparisons between analytical, finite-element analysis (FEA), and experimental results are presented, which confirm the ability of fractional-slot concentrated winding SPM machines to achieve their high-speed operating objectives. Important issues including the machine's back EMF voltage at top speed, eddy-current losses in the magnets, and inverter performance are analyzed and discussed in detail.
161 citations
TL;DR: It has been demonstrated that nanoelectrospray analysis provides a highly efficient and accurate analytical methodology to analyze PAMPA samples generated in early drug discovery.
46 citations
TL;DR: In this paper, the authors developed a general analytical technique to evaluate the integral of the dyadic Green's function without the need to specify an exclusion volume, which can be used for integration over any shape of spatial discretization cell.
Abstract: The Dyadic Green’s function is in general viewed as a generalized, or distribution function. A commonly used procedure to evaluate its volume integral is the principal-volume method, in which an infinitesimal volume around the singularity is excluded from the integration volume. In this paper, we develop a general analytical technique to evaluate the integral of the dyadic Green’s function without the need to specify an exclusion volume. The newly derived expressions accurately integrate the singularity and can be used for integration over any shape of spatial discretization cell. We derive explicit expressions for the integral of the 3D dyadic Green’s function over a sphere and over a general rectangular block. Similar expressions are obtained for the 2D dyadic Green’s function over a cylinder and over a general rectangular cell. It is shown that using the integration technique described in this paper for spherical/circular cells, simple analytical expressions can be derived, and these expressions are exactly the same as those obtained using the principal-volume method. Furthermore, the analytical expressions for the integral of the dyadic Green’s function are valid regardless of the location of the observation point, both inside and outside the integration domain. Because the expressions only involve surface integrals/line integrals, their evaluation can be performed very efficiently with a high degree of accuracy. We compare our expressions against the equivalent volume approximation for a wide 48 Gao, Torres-Verdin, and Habashy range of frequencies and cell sizes. These comparisons clearly show the efficiency and accuracy of our technique. It is also shown that the cubic cell (3D) and the square cell (2D) can be approximated with an equivalent spherical cell and circular cell, respectively, over a wide range of frequencies. The approximation can be performed analytically, and the results can be written as the value of the dyadic Green’s function at the center multiplying a “geometric factor”. We describe analytical procedures to derive the corresponding geometric factors.
43 citations
TL;DR: An analytical technique to solve the Eulerian advection-diffusion equation for nonstationary conditions and passive contaminant within the Planetary Boundary Layer is analysed and produces comparable results when considering the ground level concentration distribution.
Abstract: An analytical technique to solve the Eulerian advection-diffusion equation for nonstationary conditions and passive contaminant within the Planetary Boundary Layer is analysed in this paper. The approach produces comparable results when considering the most important quantity in air-pollution application, that is the ground level concentration distribution. This is a promising result as this computer-based technique may be used for quantitative and qualitative estimations of contaminant distribution.
17 citations
Patent•
02 Sep 2005
TL;DR: In this article, a library of materials is provided in a plurality of locations on a substrate, including first regions that are sufficiently transparent to a first form of radiation to permit analysis of the portion of the sample material supported in the first region using a first analytical technique, and second regions that were insufficiently transparent to the second form, but are sufficient to support analysis of a portion of sample material in the second region using the first analytical techniques.
Abstract: Apparatus and methods for screening a library of materials. Materials are provided in a plurality of locations on a substrate. The locations include first regions that are sufficiently transparent to a first form of radiation to permit analysis of the portion of the sample material supported in the first region using a first analytical technique, and second regions that are sufficiently transparent to a second form of radiation to permit analysis of a portion of the sample supported in the second region using a second analytical technique, but are insufficiently transparent to the first form of radiation to permit analysis of the portion of the sample material supported in the second region using the first analytical technique. Sample materials are screened at one or more sample locations of the substrate using the first analytical technique in the first region and the second analytical technique in the second region.
17 citations
Patent•
24 Jun 2005
TL;DR: In this paper, a noncontact exhaust analysis is carried out using FTIR spectrometry without a time delay, whereby the spectra obtained from a FTIR Spectrometer are used to calculate the exhaust gas composition by means of a previously determined mathematical relationship.
Abstract: On carrying out metallurgical processes in plant components, such as, for example, a converter, knowledge of the time-dependent exhaust gas composition provides a significant aid in providing information about the process advancement. Conventional analytical methods involve taking a defined volume from the exhaust flow (7) and then analysing said exhaust sample. The disadvantage of said analytical technique based on sampling is the time delay until the analytical result can be obtained after the taking of the sample. According to the invention, a non-contact exhaust analysis is carried out using FTIR spectrometry without a time delay, whereby the spectra obtained from a FTIR spectrometer (2) are used to calculate the exhaust gas composition by means of a previously determined mathematical relationship.
10 citations
TL;DR: Sequential Injection Analysis (SIA) as discussed by the authors is a novel automated analytical technique devised to replace flow-injection analysis (FIA), which is a technique that is used in many applications.
Abstract: This article is a brief introduction to sequential-injection analysis (SIA), a novel automated analytical technique devised to replace flow-injection analysis (FIA). The principles and requirements...
8 citations
05 Dec 2005
TL;DR: In this article, the authors presented a theoretically analytical technique for determining the spectral components of high-power multilevel voltage source converters based on the extension geometrical-wall model.
Abstract: This paper presents a theoretically analytical technique for determining the spectral components of high-power multilevel voltage source converters. The technique uses double Fourier series to analyze the output waveform of multilevel asynchronous asymmetrical regular sampling SVPWM converter. The 3-D spectrum representation of the SVPWM based on the extension geometrical-wall-model is given in this article. According to the analytical method of two-level SVPWM and the phase-shifted carrier PWM, the new DFS of multilevel SVPWM of single phase is obtained. In order to validate the theoretically analytical method, a six modules cascaded H-bridge converter model using PSCAD is built. By comparing the spectrum and waveform calculated with the simulation, the correctness of the analytical formulas has been proved. And the technique can act as the method of selection PWM. Moreover, the technique can be used to analyze the output waveform of the high-voltage and high-power FACTS equipments, such as SVG, SSSC, UPQC
6 citations
Patent•
27 Sep 2005
TL;DR: In this article, an analytical technique for the quantitative determination of an analyte and a reagent solution useful in said quantitative determination is presented, which is adapted for the determination of carbonyl and even more particularly adapted for finishing an alcohol produced in the Oxo Process.
Abstract: The invention relates to an analytical technique for the quantitative determination of an analyte and a reagent solution useful in said quantitative determination. The analytical technique is conveniently adapted for quantitative determination of carbonyl and even more particularly adapted for finishing an alcohol produced in the Oxo Process.
TL;DR: In this article, a review of analytical challenges and the analytical methodologies developed and also the future needs of analytical chemist are presented in this paper, and a brief review of these analytical challenges are presented.
Abstract: Available analytical literature reveals that it is possible to identify a lot of procedures to carry out any determination using a plethora of analytical techniques. The fundamental analytical requirements for realizing the desired and acceptable information from a chemical analysis are representative nature of the sample, precision, accuracy, selectivity and sensitivity. These decide, to a larger extent, the selection of the most appropriate methodology in order to obtain chemical information from a system. A number of analytical methodologies are being used in the author’s laboratory for carrying out trace elemental analysis as a part of chemical quality control. Quite a good number of analytical challenges with specific reference to the characterization of high purity materials of relevance to nuclear technology were addressed and methodologies were developed for trace elemental analysis of both metallic and non-metallic constituents. A brief review of these analytical challenges and the analytical methodologies developed and also the future needs of analytical chemist are presented in this paper.
TL;DR: The theory of Morphological Indicators (MI) has been successfully used to optimize a range of structures analytically for a chosen criterion as discussed by the authors, but these structures are mainly statically determined and subjected to simple load cases.
Abstract: The theory of Morphological Indicators (MI) has been successfully used to optimize a range of structures analytically for a chosen criterion [1]. These structures are mainly statically determined and subjected to simple load cases. When considering more complex structural systems and/or load cases, analytical techniques are inadequate and therefore numerical techniques must be used. In this paper a short general introduction of the MI is given and the current results are presented. The bottlenecks of analytical technique are discussed as more complex (hybrid) structures and load cases are considered. It is demonstrated how semi-numerical and numerical techniques can be combined with the MI to enable the optimization of these complex load cases and structures in the early design stages. Finally some examples are presented.
01 Jan 2005
TL;DR: In this paper, the authors presented a theoretically analytical technique for determining the spectral components of high-power multilevel voltage source converters using double Fourier series to analyze the output waveform of multi-level asynchronous asymmetrical regular sampling SVPWM converter.
Abstract: This paper presents a theoretically analytical technique for determining the spectral components of high- power multilevel voltage source converters. The technique uses Double Fourier Series to analyze the output waveform of multilevel asynchronous asymmetrical regular sampling SVPWM converter. The 3-D spectrum representation of the SVPWM based on the extension geometrical-wall-model is given in this article. According to the analytical method of two-level SVPWM and the phase-shifted carrier PWM, the new DFS of multilevel SVPWM of single phase is obtained. In order to validate the theoretically analytical method, a six modules cascaded H-bridge converter model using PSCAD is built. By comparing the spectrum and waveform calculated with the simulation, the correctness of the analytical formulas has been proved. And the technique can act as the method of selection PWM. Moreover, the technique can be used to analyze the output waveform of the high-voltage and high-power FACTS equipments, such as SVG, SSSC, UPQC.
01 Dec 2005
TL;DR: This work considers the interplay between fiber nonlinearity and crosstalk signals over long distance as the source of performance degradation, measured in terms of Q factor, in high-speed all-optical networks.
Abstract: In high-speed all-optical networks, nodes are able to switch signals in the optical domain, without any electronic conversion or signal regeneration. These networks are prone to optical leaks (crosstalk) within the switches. Because of the lack of regeneration, crosstalk can propagate over very long distances along with legitimate signals. In this work, we consider the interplay between fiber nonlinearity and crosstalk signals over long distance as the source of performance degradation, measured in terms of Q factor. We present an analytical crosstalk model for all-optical networks and give expressions for the performance degradation resulting from the joint propagation of a signal and crosstalk in large networks. This analytical technique uses a continuous wave assumption and is based on perturbation theory. Analytical calculations required by this model are much less computationally intensive than simulations. Simulations are carried out to validate our analytical model and good agreement is found between the analytical model and simulations.
01 Jan 2005
TL;DR: In this article, a non-destructive analytical technique known as charged particle activation analysis (CPAA) is described, based on the capability of high-energy charged particles directed on a bulk sample to induce in it nuclear reactions.
Abstract: This article describes in some detail the non-destructive analytical technique known as charged particle activation analysis (CPAA). It is based on the capability of high-energy charged particles directed on a bulk sample to induce in it nuclear reactions. By measuring the following nuclear emissions, it is possible to determine the presence and the concentration of the chemical elements contained in the sample. Through several sections, this article delineates the most important features of this technique. It covers the physical concepts involved, such as the stopping power, the particle range and the threshold energy to trigger suitable nuclear reactions. It delineates qualitatively and quantitatively the procedure to determine the concentration of the chemical elements found in the sample by comparison with standards. Subsequently, the phases of the experimental procedure are described: production of energetic ions by accelerators; samples irradiation; radiation measurement; chemical etching; radiochemical separation. The last section describes the applications of CPAA indicating the areas where its sensitivity is high and where it is low, advising the joint use of CPAA and NAA whose sensitivities are complementary. At the end of the article, some related scientific and technical literature is also provided.
01 Jan 2005
TL;DR: The photon activation analysis (PAA) is a non-destructive analytical technique based on the capability of high-energy photons (γ-rays or X-rays) to trigger nuclear reactions in atomic nuclei whose emissions can be detected to determine the chemical elements contained in a sample as mentioned in this paper.
Abstract: The present article describes in some detail the nondestructive analytical technique known as photon activation analysis (PAA). It is based on the capability of high-energy photons (γ-rays or X-rays) to trigger nuclear reactions in atomic nuclei whose emissions can be detected to determine the chemical elements contained in a sample. The article is divided into several sections, which delineate the most important feature of this analytical technique. A short historical introduction sketches the first attempts of photodisintegration that brought from light and fissile elements to stable heavy elements. A further section describes the processes involved in the photonuclear reactions, the possible interferences and the determination of the activity and the analytical sensitivity. The article gives some details of the electron accelerators to produce by Bremsstrahlung high intensity photon fluxes. It describes the sample preparation, irradiation and the photon spectrometry. A further section delineates the analytical procedures, the calibration, the sources of errors and the quality controls for light and heavy elements. The last part concentrates on the analytical applications: environmental studies, geochemical materials, biological/biomedical applications, forensic studies, cultural heritage, food applications. The article is concluded with a list of documents of the literature dedicated to the subject.
TL;DR: The analytical technique used to measure hydrocarbons is based on a Flame Ionisation Detector (FID) as mentioned in this paper, which is crucial parameters for analytical quantification of H2 emissions.
Abstract: The automotive industry is developing new technologies to meet Euro 4 and Euro 5 emissions standards. These developments have to be qualified using appropriate analytical equipment to accurately characterize and quantify emissions. The analytical technique used to measure hydrocarbons is based on a Flame Ionisation Detector (FID). Research and Development of Air Liquide Group presents crucial parameters for analytical quantification of hydrocarbons.
TL;DR: In this paper, an analytical result by the inclusion element model is greatly dependent on approach to division of the subcell, but if it is same or lower level number of elements as the real model, it was shown that the sufficient result was obtained.
Abstract: As one of the analytical technique of mechanical behavior for the textile composites, inclusion element method by the subcell division was proposed, and the verification on the effectiveness was carried out. In the inclusion element method, it is possible to analyze using very simple grid finite element, obtaining the element siffiness by the inclusion method by cooperation with the fabric structure simulator. As a result of comparing with the real model analysis, it was shown that peculiar condition of the woven composites in the deformation behavior is confirmed and the internal stress is also estimable. The analytical result by the inclusion element model is greatly dependent on approach to division of the subcell, but if it is same or lower level number of elements as the real model, it was shown that the sufficient result was obtained.
TL;DR: The results show that the homotopy technique can give much better approximation than given by perturbation techniques and can be used to obtain formula uniformly valid for both small and large parameters in non-linear problems.
24 Oct 2005
TL;DR: In this article, an analytical technique has been developed to predict air gap magnetic flux density and open-circuit voltage in large synchronous machines with a skewed stator, based on the permeance model.
Abstract: Numerical methods used in machine analysis can be very accurate, however, they can also be exceptionally time-consuming. A combined approach, when numerically obtained data are used in an analytical model, has been proposed as a solution to this problem. Unfortunately, test validation of air gap flux density models in large synchronous machines is difficult to obtain. In this work, based on the permeance model, an analytical technique has been developed to predict air gap magnetic flux density and open-circuit voltage in large synchronous machines with a skewed stator. Simulation results compare well with both rated characteristics and test measurement.