A multi-spectral reordering technique for the full spectrum SLMB modeling of radiative heat transfer in nonuniform gaseous mixtures

A Multi-Spectral Reordering (MSR) scheme is introduced to improve the performances of the Spectral-Line Moment-Based (SLMB) modeling for the handling of full spectrum radiative heat transfer calculations in nonuniform media. Using this simultaneous reordering of the spectrum for several thermophysical conditions together with employing approximate formulations to evaluate path-averaged transmission functions for nonisothermal and nonhomogenous gaseous paths, a novel full spectrum gas radiation modeling method in nonuniform gaseous mixtures is constituted. The method is presented in details as well as the building of associated databases for CO₂ and H₂O at atmospheric pressure and for the temperature range of 300-2700 K. The new model is validated against line-by-line reference computations for a series of existing benchmarks and for a flame configuration. The MSR-SLMB modeling is shown to perform accurately and better than the standard SLMB one, while involving reasonable additional computational costs.     

The spectral-line moment-based (SLMB) modeling of the wide band and global blackbody-weighted transmission function and cumulative distribution function of the absorption coefficient in uniform gaseous media

The spectral-line moment-based (SLMB) modeling is proposed for the calculation of radiative properties of gases on any spectral width. The associated mathematical formulation is obtained by applying several concepts of the k-distribution methods such as the reordering of the wavenumber scale by monotonic variations of the absorption coefficient, together with the application of the k-moment method's principles. This approach gives both a general formula for the BTF and a simple and readily applicable approximation for the blackbody-weighted cumulated k-distribution function of the absorption coefficient. The model is applied for the computation of wide band BTFs and cumulative k-distributions for uniform columns of CO₂ and H₂O in the temperature range (300-2400 K) at atmospheric pressure. Model parameters are deduced from line-by-line (LBL) spectra calculated using the HITEMP database. Comparisons with LBL reference data as well as with contemporary modeling approaches (SLW, FSK, SNB) are performed and discussed.     

Effect of acoustic waves on the repetition frequency of high repetition rate TEA-CO2 lasers and calculating optimization condition

The gas channel of a pulse periodic TEA-CO₂ laser is considered as an acoustic resonator. In this paper, a three-dimensional mathematical modeling has been considered for describe of laser action. By calculating of the equations obtained from this model, the effects of cavity dimensions, Mach number and repetition frequency of laser on the acoustic wave spectrum have been investigated. At last optimum conditions for performance of laser operation has been arrived.     

Study on the optimal algorithm prediction of corn leaf component information based on hyperspectral imaging

Genetic algorithm (GA) has a significant effect in the band optimization selection of Partial Least Squares (PLS) correction model. Application of genetic algorithm in selection of characteristic bands can achieve the optimal solution more rapidly, effectively improve measurement accuracy and reduce variables used for modeling. In this study, genetic algorithm as a module conducted band selection for the application of hyperspectral imaging in nondestructive testing of corn seedling leaves, and GA-PLS model was established. In addition, PLS quantitative model of full spectrum and experienced-spectrum region were established in order to suggest the feasibility of genetic algorithm optimizing wave bands, and model robustness was evaluated. There were 12 characteristic bands selected by genetic algorithm. With reflectance values of corn seedling component information at spectral characteristic wavelengths corresponding to 12 characteristic bands as variables, a model about SPAD values of corn leaves acquired was established by PLS, and modeling results showed r = 0.7825. The model results were better than those of PLS model established in full spectrum and experience-based selected bands. The results suggested that genetic algorithm can be used for data optimization and screening before establishing the corn seedling component information model by PLS method and effectively increase measurement accuracy and greatly reduce variables used for modeling.     

Application of approximations for joint cumulative k-distributions for mixtures to FSK radiation heat transfer in multi-component high temperature non-LTE plasmas

Approximations for joint cumulative k-distribution for mixtures are efficient for full spectrum k-distribution (FSK) computations. These approximations provide reduction of the database that is necessary to perform FSK computation when compared to the direct approach, which uses cumulative k-distributions computed from the spectrum of the mixture, and also less computational expensive when compared to techniques in which RTE's are required to be solved for each component of the mixture. The aim of the present paper is to extend the approximations for joint cumulative k-distributions for non-LTE media. For doing that, a FSK to non-LTE media formulation well-suited to be applied along with approximations for joint cumulative k-distributions is presented. The application of the proposed methodology is demonstrated by solving the radiation heat transfer in non-LTE high temperature plasmas composed of N, O, N₂, NO, N₂⁺ and mixtures of these species. The two more efficient approximations, that is, the superposition and multiplication are employed and analyzed.     

Evaluation of solution methods for radiative heat transfer in gaseous oxy-fuel combustion environments

The exact solution to radiative heat transfer in combusting flows is not possible analytically due to the complex nature of the integro-differential radiative transfer equation (RTE). Many different approximate solution methods for the solution of the RTE in multi-dimensional problems are available. In this paper, two of the principal methods, the spherical harmonics (P₁) and the discrete ordinates method (DOM) are used to calculate radiation. The radiative properties of the gases are calculated using a non-gray gas full spectrum k-distribution method and a gray method. Analysis of the effects of numerical quadrature in the DOM and its effect on computation time is performed. Results of different radiative property methods are compared with benchmark statistical narrow band (SNB) data for both cases that simulate air combustion and oxy-fuel combustion. For both cases, results of the non-gray full spectrum k-distribution method are in good agreement with the SNB data. In the case of oxy-fuel simulations with high partial pressures of carbon dioxide, use of gray method for the radiative properties may cause errors and should be avoided.     

Variable order spherical harmonic expansion scheme for the radiative transport equation using finite elements

We propose the P_N approximation based on a finite element framework for solving the radiative transport equation with optical tomography as the primary application area. The key idea is to employ a variable order spherical harmonic expansion for angular discretization based on the proximity to the source and the local scattering coefficient. The proposed scheme is shown to be computationally efficient compared to employing homogeneously high orders of expansion everywhere in the domain. In addition the numerical method is shown to accurately describe the void regions encountered in the forward modeling of real-life specimens such as infant brains. The accuracy of the method is demonstrated over three model problems where the P_N approximation is compared against Monte Carlo simulations and other state-of-the-art methods.     

Separation of variables for integrable spin–boson models

We formulate the functional Bethe ansatz for bosonic (infinite dimensional) representations of the Yang–Baxter algebra. The main deviation from the standard approach consists in a half infinite Sklyanin lattice made of the eigenvalues of the operator zeros of the Bethe annihilation operator. By a separation of variables, functional TQ-equations are obtained for this half infinite lattice. They provide valuable information about the spectrum of a given Hamiltonian model. We apply this procedure to integrable spin–boson models subject to both twisted and open boundary conditions. In the case of general twisted and certain open boundary conditions polynomial solutions to these TQ-equations are found and we compute the spectrum of both the full transfer matrix and its quasi-classical limit. For generic open boundaries we present a two-parameter family of Bethe equations, derived from TQ-equations that are compatible with polynomial solutions for Q. A connection of these parameters to the boundary fields is still missing.     

Possibilities of the observation of the discrete spectrum of the water dimer at equilibrium in millimeter-wave band

Attempts of experimental observations of the water dimer spectrum at equilibrium conditions have lasted for more than 40 years since the dimeric hypothesis for extra absorption, but have not yielded any positive confirmed result. In the present paper a new approach is considered: using a high-resolution millimeter-wave spectrum of the water dimer at equilibrium, calculated by a rigorous fully quantum method, we show the potential existence of discernible spectral series of discrete features of the water dimer, which correspond to J+1←J, K lines of E₁ symmetry, already observed in cold molecular beam experiments and having, therefore, well-defined positions. The intensity of spectral series and contrast to the remaining continuum-like spectrum of the dimer are calculated and compared with the monomer absorption. The suitability of two types of microwave spectrometers for observing these series is considered. The collisional line-width of millimeter lines of the dimer at equilibrium is estimated and the width of IR dimer bands is discussed. It is pointed out that the large width of IR dimer bands may pose difficulties for their reliable observation and conclusive separation from the rest of absorption in water vapor. This situation contrasts with the suggested approach of dimer detection in millimeter-waves.     

Narrow-band and full-spectrum k-distributions for radiative heat transfer—correlated-k vs. scaling approximation

The correlated-k and scaled-k distribution methods for radiative heat transfer in molecular gases are developed based on precise mathematical principles, for both narrow band and full spectrum models. Their differences and commonalities are high-lighted and discussed. Applications to narrow spectral bands of nonhomogeneous gases show both methods to be about equally accurate. For full-spectrum calculations, on the other hand, the scaled-k distribution consistently outperforms the correlated-k model.     

The binding of 3-(p-bromophenyl)-5-methyl-thiohydantoin with human serum albumin: Investigation by fluorescence spectroscopy and molecular model

The binding of 3-(p-bromophenyl)-5-methyl-thiohydantoin (BPMT) with human serum albumin (HSA) was investigated by fluorescence spectroscopy in combination with UV absorption spectrum under physiological conditions. The intrinsic fluorescence of HSA was quenched by BPMT through static quenching mechanism and the fluorescence emission spectrum of HSA exhibited appreciable hypsochromic shift with increasing concentration of BPMT. The binding constants (K) of HSA with BPMT and the number binding sites (n) at different temperatures, thermodynamic parameter enthalpy changes (ΔH) and entropy changes (ΔS) of HSA-BPMT have been calculated according to the relevant fluorescence data, indicating that the hydrophobic interaction played a major role, which was consistent with the result of molecular modeling study.     

Assignment Strategies and Analysis of Cross-Peak Patterns and Intensities in the Three-Dimensional Homonuclear TOCSY-NOESY of RNA

The application of 3D TOCSY-NOESY to the analysis of RNA is presented, using a TOCSY-NOESY spectrum of the RNA duplex r(5′GGGCUGAAGCCU′). It is shown that for RNA molecules, 3D spectra can be obtained with a digital resolution comparable to that obtained for 2D NMR with full spectral information. The improvement in assignment over 2D methods is shown and discussed on the basis of an assignment strategy presented earlier. A simple and straightforward method for determining sugar puckers and γ backbone torsion angles is presented, which is derived from an analysis of cross-peak intensities originating from the TOCSY coherence transfer among sugar protons and HS′/5″ protons. The stereospecific assignment of the HS′/5″ resonances in 3D TOCSY-NOESY spectra is also discussed.     

小波变换与神经网络融合法在油页岩近红外光谱分析中的应用

便携式近红外光谱分析技术可实现油页岩含油率的原位检测,在油页岩资源现场勘查中发挥着重要作用。但是,由于其测得的原始光谱数据量大、冗余信息多,直接建模会影响速度与精度。因此提出一种小波变换与神经网络融合法,先将油页岩全谱数据进行db8小波3级分解,提取其近似系数形成输入矩阵,然后再进行神经网络建模。为了验证有效性,利用30个油页岩合成样品,从中随机选择20个用于训练,另外10个用于预测,并分别使用全谱数据与小波特征数据进行了10次神经网络建模。结果表明,全谱数据建模速度均值为570.33 s,预测残差平方和及相关系数均值分别为0.006 012及0.843 75;而小波神经网络法对应的以上均值为3.15 s, 0.002 048及0.953 19。由此说明小波神经网络法优于全谱数据建模法,为油页岩含油率的快速、高精度检测提供了一种新方法。     

油页岩含油率近红外光谱原位分析方法研究

为实现油页岩含油率的原位检测,采用便携式近红外光谱分析技术,针对吉林扶余油页岩基地2号钻井的66个岩芯样品开展了原位检测的分析建模方法研究。采用自制便携式近红外光谱仪器获得反射率、吸光度、K-M函数三种数据形式光谱数据,结合主成分-马氏距离(PCA-MD)剔除异常样品、无信息变量消除法(UVE)波长筛选及二者组合的四种建模数据优化方法,采用相同的数据预处理方法进行偏最小二乘(PLS)和反向传播神经网络(BPANN)两种方法的建模分析研究,确定最佳分析模型及方法。结果表明(1)不论是否采用四种不同的数据优化方法,两种建模方法所用建模数据库适合采用反射率或K-M函数的光谱数据形式;(2)两种建模方法,采用四种不同的数据优化方法,对相同数据库建模精度的影响不同：采用PLS建模方法、以PCA-MD和UVE+ PCA-MD两种方法进行数据优化、可以提高K-M函数光谱数据形式数据库的建模分析精度,采用BPANN建模方法、以UVE、PCA-MD 与UVE组合的 三种方法进行数据优化、对三种数据形式数据库的建模精度均有所提高;(3)除以反射率光谱数据并进行PCA-MD数据优化外,采用BPANN方法的建模精度好于PLS法。其中采用反射率光谱数据形式、只进行UVE数据优化外的BPANN建模精度最高,预测相关系数为0.92、标准偏差为0.69%。     

Neuroradiologic MR applications with multiparametric color composite display

The purpose of this article is to demonstrate the application of a PC-based multiparameter full color composite display technique of MR images of 14 selected patients with neuropathology while assessing the ability of this technique to display clinically important neuroanatomic and neuropathologic tissues. Using a PC with a 386 microprocessor and full color 24-bit graphics display capabilities, custom and commercially available image-processing softwares were applied to spatially aligned multiparameter proton density, T₁-weighted (with and/or without gadolinium-DTPA) and T₂-weighted MR image sets obtained from 14 patients with known neuropathology to generate intensity-based color composites. Quantitative color channel applications were used to assess the ability of this technique to differentiate anatomically and pathologically confirmed tissue types into unique color regions within the full color spectrum display in each patient case. Based on the results of pathologic correlation and quantitative color imaging analysis, the application of full color composite generation techniques to multiple MR images of selected neuropathology cases represents a viable technique for displaying diagnostically relevant tissue contrast information in one color image. With this technique, it is possible to generate composites that simultaneously display uniquely color-coded neuroanatomic and neuropathologic tissue information within the context of partially natural-appearing images.     

The 2003 edition of the GEISA/IASI spectroscopic database

The content of the current (2003) version, GEISA/IASI-03, of the computer-accessible spectroscopic database, GEISA/IASI, is described. This “system” or database is comprised of three independent spectroscopic archives, which are (a) a database of individual spectral line parameters on 14 molecules, H₂O, CO₂, O₃, N₂O, CO, CH₄, O₂, NO, SO₂, NO₂, HNO₃, OCS, C₂H₂, N₂, and the related 51 isotopomers and isotopologues, representing 702,550 entries, in the spectral range 599-, (b) a database of spectral absorption cross-sections (6,572,329 entries related to six molecules, CFC-11, CFC-12, CFC-14, HCFC-22, N₂O₅, CCl₄), and a catalogue of microphysical and optical properties (mainly, the refractive indices) of atmospheric aerosols. The modifications and improvements, which have been implemented since the earlier editions of this database, in terms of content and management, have been explained in detail. GEISA/IASI has been created with the specific purpose of assessing the capability of measurement by the IASI instrument within the designated goals of ISSWG in the frame of the CNES/EUMETSAT European Polar System preparation.All the archived data can be handled through a user-friendly associated management software, which is posted on the ARA/LMD group web site at http://ara.lmd.polytechnique.fr.     

The rotational spectrum of tertiary-butyl alcohol

The rotational spectrum of tertiary-butyl alcohol has been recorded in selected regions between 8 and 500 GHz. Early data from the University of Wisconsin in the 8-40 GHz region have been combined with recent measurements from the University of Bologna and the Jet Propulsion Laboratory in the millimeter and submillimeter wavelength regions. The spectrum was fit over a wide range of J’s and K’s using a common set of parameters for both the A and E states. This paper describes the initial assignment at Wisconsin and the final procedure used to assign and fit the higher rotational states. The resulting molecular constants and their interpretation are discussed.     

Skeletal mechanism generation with CSP and validation for premixed n-heptane flames

An automated procedure has been previously developed to generate simplified skeletal reaction mechanisms for the combustion of n-heptane/air mixtures at equivalence ratios between 0.5 and 2.0 and different pressures. The algorithm is based on a Computational Singular Perturbation (CSP)-generated database of importance indices computed from homogeneous n-heptane/air ignition solutions. In this paper, we examine the accuracy of these simplified mechanisms when they are used for modeling laminar n-heptane/air premixed flames. The objective is to evaluate the accuracy of the simplified models when transport processes lead to local mixture compositions that are not necessarily part of the comprehensive homogeneous ignition databases. The detailed mechanism was developed by Curran et al. and involves 560 species and 2538 reactions. The smallest skeletal mechanism considered consists of 66 species and 326 reactions. We show that these skeletal mechanisms yield good agreement with the detailed model for premixed n-heptane flames, over a wide range of equivalence ratios and pressures, for global flame properties. They also exhibit good accuracy in predicting certain elements of internal flame structure, especially the profiles of temperature and major chemical species. On the other hand, we find larger errors in the concentrations of many minor/radical species, particularly in the region where low-temperature chemistry plays a significant role. We also observe that the low-temperature chemistry of n-heptane can play an important role at very lean or very rich mixtures, reaching these limits first at high pressure. This has implications to numerical simulations of non-premixed flames where these lean and rich regions occur naturally.     

多元校正结合质谱数据进行四种有机物快速含量分析研究

质谱法和化学计量学方法相结合对混合物中苯甲醛,异辛烷,乙酸丁酯,苯乙酮四种物质进行定量分析。将混合物的质量色谱图数据分别用特征选择-多元线性回归（MLR）和全谱-偏最小二乘法（PLS）这两种方法对四种物质进行定量分析。苯甲醛特征选择和全谱建模的RMSEP分别为0.062和0.091; 异辛烷特征选择和全谱建模的RMSEP分别为0.048和0.057; 乙酸丁酯特征选择和全谱建模的RMSEP分别为0.021和0.020; 苯乙酮特征选择和全谱建模的RMSEP分别为0.010和0.032。结果表明苯甲醛,异辛烷,苯乙酮特征选择的结果均优于全谱建模的结果,乙酸丁酯特征选择的结果和全谱建模的结果相近。