Determination of ion-broadening parameter for some Ar I spectral lines

This paper presents the results of the ion-broadening parameter A determination from experimental profiles of several neutral argon lines. Advanced deconvolution procedure has been used for parameter A determination. Experimental results have been obtained from the wall-stabilized pure argon plasma with electron density range (0.74-2.90) and temperature range 9280-. These results are compared with available theoretical and other experimental data.     

Exact analytical formula for Voigt spectral line profile

An analytical formula for the Voigt spectral line profile has been derived. The obtained formula is the solution of the second-order differential equation of the Voigt profile. The obtained results using the new analytical formula are in perfect agreement with the published results obtained by numerical calculation methods for a wide range of the line damping parameter (a) . The accuracy of the obtained formula is found to be 100% for all ranges of the line damping parameter (a).     

Simulated annealing algorithm for ill-posed or ill-conditioning deconvolution problem

I.IlitroductiollDeconvolutionisesselltialinsomeenglneeringapplications.Forexample,toexaminethepropertiesofmaterial8withoutbrealdngthemdownNonDestructiveEvaluationTechniquesNDETareusuallyusedandmainlybasedontheultrasonicmeasurementwherebroadbandultrasonicpulsesaJrecoupledintothematerichandtheechoesarecollected.Thenthepulseresponseofthematerialisdeconvolutedandthecharacteristicsofthehiddenflawsinthematerialscanbeidentifiedbypatternrecoghtiontechulqllesl1l.DeconvolutionisaIsoencounteredinthe…     

Speech dereverberation method based on spectral subtraction and spectral line enhancement

Speech signals recorded with a distant microphone usually are interfered by the spatial reverberation in the room, which severely degrades the clarity and intelligibility of speech. A speech dereverberation method based on spectral subtraction and spectral line enhancement is proposed in this paper. Following the generalized statistical reverberation model, the power spectrum of late reverberation is estimated and removed from the reverberation speech by the spectral subtraction method. Then, according to the human auditory model, a spectral line enhancement technique based on adaptive post-filtering is adopted to further eliminate the reverberant components between adjacent speech formants. The proposed method can effectively suppress the spatial reverberation and improve the auditory perception of speech. The subjective and objective evaluation results reveal that the perceptual quality of speech is greatly improved by the proposed method.     

A new approach to the inverse scattering and spectral problems for the Sturm-Liouville equation

New proofs of the known uniqueness theorems for the one-dimensional inverse spectral and scattering problems are given. Proof of the invertibility of all of the steps in the inversion procedures of Gelfand-Levitan and Marchenko is given. The proposed method of investigation yields some new results, for example, a Marchenko-type equation at x = 0 which holds on the whole axis, rather than on a half-axis, as usual for the scattering theory on half-axis. It also yields a new method, shorter and simpler than earlier published, for proving that the potential in the class L_1,1, obtained by the Marchenko reconstruction procedure, generates the scattering data from which it was reconstructed.     

Investigation of Hg resonance 184.9 nm line profile in a low-pressure mercury-argon discharge

The line profiles of 184.9 nm Hg resonance line emitted from a Hg low-pressure high-frequency electrodeless discharge lamp, containing Hg 198 isotope, have been measured by means of a Zeeman scanning spectrometer at the mercury cold spot temperature values in the range of 0-23 °C. Two different methods were used to determine the real spectral line profile and to separate the instrument function: (i) solving the ill-posed inverse problem by means of the Tikhonov's regularization method; and (ii) the mathematical modelling by means of a non-linear multi-parameter chi-square fit. The real Hg 184.9 nm spectral line profiles, determined by both methods, are compared. Influence of instrumental function, degree of the self-absorption and temperature of the radiating atoms are obtained.     

超声检测中维纳逆滤波解卷积方法的改进研究

维纳逆滤波是利用解卷积技术提高超声检测纵向分辨率的算法之一。本文分析了其传统算法 对噪声适应性不理想的原因,提出一种改进方法,利用检测系统信噪比先验知识,进行频域解卷积处 理,在此基础上,对检测系统频带内的处理结果建模,插补估计出频带外受噪声干扰影响较大的数 据,然后再变换到时域。计算机模拟及相应实验结果表明,这些改进方法较为理想,具有较强的噪声 适应能力。     

The Bernese atmospheric multiple catalog access tool (BEAMCAT): a tool for users of popular spectral line catalogs

Users of spectroscopic data bases in the microwave region quickly realize that each existing spectral line catalog provide only part of the information that they would like to have. As a workaround for this problem, several merged spectral line data bases have been created by different groups. However, these merged data bases are usually very specific for a certain application and are difficult to maintain. The BEAMCAT data base takes a totally new approach that makes it possible to generate merged spectral line catalogs from any number of source catalogs in multiple user-defined formats. The current version of BEAMCAT contains the complete JPL and HITRAN catalog. Other catalogs like GEISA will soon be included, too.As a first application of the BEAMCAT data base, the author conducted a thorough intercomparison of spectral parameters for all the transitions that the JPL catalog and HITRAN have in common. The intercomparison shows that the spectral parameters in the catalogs are by no means identical. While the difference in center frequency is usually small, the differences in line intensity reach from almost exact match to discrepancies of several orders of magnitude. While it cannot be ruled out that some of the lines were matched incorrectly, this intercomparison might be helpful to identify problems with the original catalogs.     

Calculation of solar radiation atmospheric absorption with different H2O spectral line data banks

A comparison of the atmospheric absorption calculated with different data banks of water vapour absorption lines is made. The HITRAN database, Barber-Tennyson line list (BT2), calculation of Partridge and Schwenke (PS) are considered. The contribution of H₂O lines, absent in HITRAN, to the atmospheric transmission, calculated with 10 cm⁻¹ spectral resolution in the 10 000-20 000 cm⁻¹ spectral region is up to 1.5% for a vertical path and 4% for a solar zenith angle of 70 deg. The highest difference is observed in the 940 nm band. The incoming fluxes of solar radiation, measured by a rotating solar spectroradiometer, were modeled with BT2 and HITRAN database. The difference between measured and calculated fluxes does not exceed the instrumental uncertainties.     

GOSAT-2009 methane spectral line list in the 5550-6236 cm range

A methane spectral line list for the 5550-6236 cm⁻¹ range with the intensity cut off 4×10⁻²⁶ cm/molecule at 296 K is presented. The line list is based on new extensive measurements of methane spectral line parameters performed at different temperatures and pressures of methane and buffer gases N₂, O₂ and air. This spectral line list is prepared in HITRAN-2008 format and contains the following spectral line parameters of about 11,000 lines: position, intensity, energy for lower state (where possible), air-broadening and air-shifting coefficients, exponent of temperature dependence of air-broadening coefficient and self-broadening coefficient.     

Using Fast Fourier Transform to compute the line shape of frequency-modulated spectral profiles

An expression for the shape of spectral lines recorded by sinusoidal frequency modulation and harmonic detection is derived. It can be fast computed by means of the Fast Fourier Transform method and it holds for any modulation depth and modulation frequency. Different line shape functions, such as Voigt, Galatry, and speed-dependent Voigt, may be included in the model. In this work, the performance of the computing method is tested with experimental second harmonic rotational profiles, but it can be applied to higher harmonic spectra as well.     

光谱线型函数的四种形式及其变换关系

从理论上研究了光谱线型函数的四种形式及其关系,以多普勒展宽导致的线型函数为例,分析了光子数、能量按频率及波长分布函数的最大值和半高全宽。结果表明,光子数、能量按频率的分布函数近似相等,光子数、能量按波长的分布函数也近似相等。通过对多普勒线型函数的分析,建立了根据两条光谱线的线型函数的最大值比值求得光子数比值的方法。     

Optimization of deconvolution in Compton profile measurements

The method of generalized least squares has been used to deconvolute the Compton profile measurements in nickel. The method depends on two arbitrary parameters namely the cut-off parameterK and the damping factor λ. This has been discussed and a method suggested to optimize the damping parameter.     

Analytical approximations for speed-dependent spectral line profiles

Analytical approximate expressions for speed-dependent Rautian-Sobel'man, Voigt, and general line profiles, including spectral line mixing, were obtained. Systematic errors of the approximate profiles are within 0.7% for the mass ratios of perturbing and absorbing molecules m_b/m_a≤9. The calculation time of the approximate line profiles is much shorter than the time required for calculating exact expressions for the line profiles. An approximate analytical expression for the observable homogeneous line width was derived. A least-square fitting of the singlet methane absorption line centered at 6107.17 cm⁻¹ was performed, using the approximate line profiles obtained.     

A new technique for the identification of ultrasonic flaw signals using deconvolution

The identification of ultrasonic flaw signals is a difficult task in the angle beam ultrasonic testing of welded joints due to the presence of non-relevant signals from the geometric reflectors such as weld-roots and counter-bores. This paper describes a new approach to identify ultrasonic flaw signals in such a problematic situation. A similarity function is defined as the deconvolution of a target signal by a reference signal. The similarity functions for the same type of flaws/references are symmetric bandlimited impulse-like patterns with larger amplitudes while those for different types of flaws/references are asymmetrical broad patterns with relatively smaller amplitudes. Therefore, ultrasonic signals could be identified by the pattern of the similarity function. In the initial experiments, the proposed technique showed great potential for identifying ultrasonic flaw signals in the inspection of weld joints.     

Implicit subgrid-scale modeling by adaptive deconvolution

A new approach for the construction of implicit subgrid-scale models for large-eddy simulation based on adaptive local deconvolution is proposed. An approximation of the unfiltered solution is obtained from a quasi-linear combination of local interpolation polynomials. The physical flux function is modeled by a suitable numerical flux function. The effective subgrid-scale model can be determined by a modified-differential equation analysis. Discretization parameters which determine the behavior of the implicit model in regions of developed turbulence can be adjusted so that a given explicit subgrid-scale model is recovered to leading order in filter width. Alternatively, improved discretization parameters can be found directly by evolutionary optimization. Computational results for stochastically forced and decaying Burgers turbulence are provided. An assessment of the computational experiments shows that results for a given explicit subgrid-scale model can be matched by computations with an implicit representation. A considerable improvement can be achieved if instead of the parameters matching an explicit model discretization parameters determined by evolutionary optimization are used.     

一种直线检测的尺蠖蠕行算法

从仿生学的角度提出了一种新的直线检测的尺蠖蠕行算法(cankerworm crawlalgorithm)。该算法首先根据梯度方向将边缘像素集合划分成为具有一定梯度范围的子集,然后采用蠕行策略在独立的边缘点的子集内进行直线提取。理论分析和实验结果证明:该方法大大减小了直线特征提取的复杂度,并且具有较好的直线检测效果。     

The determination of the true profile of XPS line by regularization method: I. Mathematical algorithm and numerical simulations

The resolution of XPS spectra is limited mainly by instrumental parameters like the spectral line width of exciting X-ray source and the finite energy resolution of the electron analyzer. A new algorithm of an inverse ill-posed problem has been proposed in which low resolution experimental XPS data can be enhanced by removing the instrumental functions. The regularization method with a special fast iteration algorithm is applied for determining the true profile line of a complex chemical compound if we know excitation and instrumental functions. This paper is structured as follows: (I) a mathematical algorithm is described and numerical simulation results are presented. (II) These algorithms have been applied to the poorly resolved C 1s spectrum of a poly-methyl methacrylate (PMMA) film studied by the conventional technique with monochromatic and polychromatic radiation. The resulting enhancement allows previously unresolved structure to be observed without any assumptions concerning number, position, shape of peaks and their ratio.     

Introduction to submillimeter, millimeter and microwave spectral line catalog

This note is an introduction to the reprint of the 1998 JQSRT paper “Submillimeter, millimeter, and microwave spectral line catalog” by H.M. Pickett et al. We describe the timeliness and significance of the article and the extensive use of our spectral line catalog as well as discuss more recent profound developments.     

Asymptotic Inverse Problem for Almost-Periodically Perturbed Quantum Harmonic Oscillator

Let be the spectrum of in L ²(ℝ), where q is an even almost-periodic complex-valued function with bounded primitive and derivative. It is known that , where is the spectrum of the unperturbed operator. Suppose that the asymptotic approximation to the first asymptotic correction is given. We prove the formula that recovers the frequencies and the Fourier coefficients of q in terms of Δμ _n .