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用AFM轮廓仪测量了ICF靶丸3个相互正交方向上的表面高度数据。分析了测量数据的误差来源,给出了消除表面异常扰动和偏心距两类误差的方法和原始数据预处理步骤,采用最小二乘法评定了靶丸球度。给出了靶丸表面形貌一维功率谱估计计算方法和表面粗糙度的计算方法。     

Accuracy enhancement of parameter estimation for noisy NMR spectra

An ARMA(M,M-1) modeling is implemented by the multi-stage linear least squares. This modeling technique is applied to the analysis of noisy NMR signals. A new method is proposed to eliminate the spurious peaks by utilizing the phase angle difference between the real and imaginary data. The proposed method is tested to simulated and experimental¹⁷O, NMR spectra with seven peaks. The results are compared to those by the autoregressive (AR) Householder triangularization decomposition (QRD). The proposed ARMA(M,M-1) model yields more accurate and consistent parameter estimation than AR model in the noisy spectra.     

Background subtraction in electron spectroscopy by use of reflection electron energy loss spectra

The use of reflected electron energy loss spectra (REELS) in deconvoluting the inelastic background signal from XPS and AES spectra from homogeneous samples is studied. It is demonstrated that under certain assumptions, the cross section for inelastic electron scattering can be extracted from a REELS spectrum. This cross section is applied to deconvolute an experimental XPS spectrum of aluminium. The method, its limitations and its relation to other methods are discussed.     

Nonperturbative simulation of two-pulse electron spin-echo-envelope modulation spectra. Comparison with experimental single-crystal spectra

The direct method of calculating magnetic observables provided by the Liouville formalism is utilized for a nonperturbative numerical treatment of electron spin-echo-envelope modulation (ESEEM). Calculated time-domain signals are compared with experimental ones. The particular system studied is the C0₂ anion trapped in NaHC₂O₄·H₂O single crystals. The experimental ESEEM spectra show modulations due to both proton and sodium nuclei. The hyperfine and quadrupole tensors, determined independently by ENDOR spectroscopy, are used as input for calculating the ESEEM spectra.     

Background removal in auger electron spectroscopy: a new experimental approach

A review of the main available methods of background removal in Auger electron Spectroscopy and X-ray photoelectron Spectroscopy is given. The major features, assumptions and results of theoretical works, which form the basis of the present method, are presented. This method uses a convolution technique of the experimental spectrum with the single event loss function. It has been applied to Auger electron spectra (Si, Ag, Fe, Ni, Cu, Al). When Auger energy is sufficiently low (Si, Ag), it has been assumed that Auger electrons act as a secondary electrons source within a multiplet energy range. In every case results are satisfactory.     

Theoretical modeling of experimental HREEL spectra for supported graphene

We present a simple model for the resonant feature designated as the π plasmon in single-layer graphene supported by a metal substrate, which is excited via high-resolution electron energy loss spectroscopy (HREELS) in the off-specular scattering geometry. Using a two-dimensional, two-fluid hydrodynamic model for interband transitions of graphene's π and σ electrons and an empirical Drude–Lorentz model for the metal in the local approximation enables us to reproduce, at the qualitative and semi-quantitative levels, the typical experimental features of the HREEL spectra in the visible to the ultraviolet frequency range.     

Useful multiparticle entanglement and sub-shot-noise sensitivity in experimental phase estimation

We experimentally demonstrate a general criterion to identify entangled states useful for the estimation of an unknown phase shift with a sensitivity higher than the shot-noise limit. We show how to exploit this entanglement on the examples of a maximum likelihood as well as of a Bayesian phase estimation protocol. Using an entangled four-photon state we achieve a phase sensitivity clearly beyond the shot-noise limit. Our detailed comparison of methods and quantum states for entanglement enhanced metrology reveals the connection between multiparticle entanglement and sub-shot-noise uncertainty, both in a frequentist and in a Bayesian phase estimation setting.     

Electronic structure and experimental spectra of some rare-earth oxyfluorides

The results of electronic structure calculations on LaOF, PrOF, NdOF and EuOF making use of the Xα discrete variational method are presented, together with experimental X-ray photoelectron and emission spectra of these compounds. The MO energy-level diagrams provide a satisfactory semiquantitative interpretation of the experimental XPS, X-ray emission, and luminescence spectra.     

阻尼最小二乘算法CARS光谱温度拟合

为了解决相干反斯托克斯喇曼散射（CARS）光谱CARSFT计算程序在温度拟合过程中,对初值依赖大、测量光谱信噪比差、不易收敛的问题,通过分析非线性迭代算法,采用了阻尼最小二乘算法对氮气CARS光谱进行温度拟合。针对CARS理论光谱计算公式较为复杂的特点,采用数值差分的方式来获得迭代计算时所需要的设计矩阵。分析了横向偏移、纵向偏移和温度三个主要参量对拟合残差的影响,发现纵向偏移的初值设置对温度拟合影响较大。拟合温度2000 K时的标准理论CARS光谱,设置偏离较大的初始值,采用阻尼最小二乘法获得了较好的结果。迭代计算167步后,温度拟合为2 005.6 K,残差为0.027 463。拟合光谱信噪比较差的CARS光谱,阻尼最小二乘法也能稳定收敛。结果验证了阻尼最小二乘法对初值的依赖不大,并且当拟合谱信噪比较差时也能收敛,可用于在恶劣环境下CARS测量光谱的拟合。     

Phenomenological model and experimental study of DNA absorption spectra in THz range

The dielectric permittivity tensor is analyzed qualitatively for the DNA nematic liquid crystal in the THz frequency range. The analysis is performed within the self-consistent phonon approximation based on the PBD model. It is found that DNA depolarization and absorption spectra depend on such parameters as molecular length and helix period. Specifically it is shown that a localization of the absorption lines in the frequency range is determined by the DNA helix structure whereas the DNA length is responsible for a separation between the absorption lines. It is also shown that the gyrotropic properties of the considered liquid crystal depend on a relation between the molecular length and its helix period. The molecules with even number of half helix periods demonstrate the strongest gyrotrophy whereas the molecules with odd number of half helix periods have the weakest gyrotrophy. The model is used to suggest the experimental methodology for determining the DNA length and helix structure based on measurements of the depolarization and absorption spectra in aqueous solutions of biopolimers. Methods of applied THz spectroscopy for determination of the conformational state of molecules in solution is announced. Some preliminary experimental results are presented, including details of measuring the absorption spectra of dry DNA sample and aqueous solutions of biopolimers.     

Theoretical and experimental power spectra of neutron monitor time series in 1978

Summary A comprehensive model for the spectral analysis of neutron monitor data is presented. The contributions to the power spectrum include scintillations in the interplanetary magnetic field caused by cosmic-ray diffusion along and perpendicularly to the field and Forbush-decrease effects. The effects of the Earth's rotation and of nonlinear interactions between particles and fields are taken into account. The model is then compared with the 1978 data of the ?polar? station of Alert and the ?quasi-equatorial? station of Deep River and the agreement is very satisfactory.

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Riassunto Si presenta un modello generale per l'analisi spettrale dei dati da monitori di neutroni. I contributi allo spettro di potenza includono le scintillazioni nel campo magnetico interplanetario dovute alla diffusione dei raggi cosmici lungo il campo e perpendicolarmente ad esso e gli effetti delle diminuzioni Forbush. Si considerano anche gli effetti della rotazione della Terra e delle interazioni non lineari fra particelle e campi. Il modello è quindi confrontato con i dati 1978 della stazione ?polare? di Alert e di quella ?quasi equatoriale? di Deep River e l'accordo risulta molto soddisfacente.

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Резюме Предлагается общая модель для спектрального анализа данных с нейтронных мониторов. Вклады в степенной спектр включают сцинтилляции в межпланетном магнитном поле, обусловленние диффузией космуческих лучей вдоль и перпендикулярно полю и эффектами ?уменьшений? форбуша. Учитываются эффекты вращения Земли и нелинейных взаимодействий между частицами и полями. Затем предложенная модель сравнивается с данными, полученными в 1978 г. на ?полярной? станции Алерт и на ?квазиэкваториальной? станции Дип Ривер. Получено удовлетворительное согласие.

     

Comparison between intensity jumps in experimental,simulated and theoretical multielemental spectra

The results obtained by applying the theory developed for the SEICXRF method and applying a Monte Carlo simulation code (MCS) are compared with the experimental data in order to validate this theory. Specifically, an assay is made with the spectra corresponding to a brass sample and a soil sample. The experimental data were corrected considering the chamber efficiency and the dead time of the detection system. The considerations taken into account in order to obtain a correct comparison between theory and experiment are discussed in detail. Good agreement between spectra is observed, taking as reference the given values of the elemental composition. The experimental intensity jumps are in agreement with those predicted by the theory and by the MCS. Copyright © 2003 John Wiley & Sons, Ltd.     

$Ab~initio$ and experimental study of the K-shell spectra of s-triazine

The carbon and nitrogen K-shell spectra of gaseous s-triazine have been studied using inner-shell electron energy loss spectroscopy (ISEELS) method. Ab initio Configuration Interaction calculations have been carried out in order to assign the observed bands. As in many similar molecules, both spectra are dominated by an intense π^* peak, followed by lower intensity features. At the C1s edge, the calculations show that some previous assignments made using an underestimated core ionisation energy of about 2.5 eV have to be revisited. At the nitrogen edge, the calculations predict a high intensity π^* doubly excited state lying below the ionisation threshold, which could be responsible for one the most intense observable bands at 405.32 eV.     

Spectral-statistics properties of the experimental and theoretical light meson spectra

We present a robust analysis of the spectral fluctuations exhibited by the light meson spectrum. This analysis provides information about the degree of chaos in light mesons and may be useful to get some insight on the underlying interactions. Our analysis unveils that the statistical properties of the light meson spectrum are close, but not exactly equal, to those of chaotic systems. In addition, we have analyzed several theoretical spectra including the latest lattice QCD calculation. With a single exception, their statistical properties are close to those of a generic integrable system, and thus incompatible with the experimental spectrum.     

Background removal from polarized Raman spectra of tooth enamel using the wavelet transform

A wavelet transformation method is introduced to remove the large fluorescence background from polarized Raman spectra of stained tooth enamel. This method exploits the wavelet multiresolution decomposition where the experimental Raman spectrum is decomposed into signals with different frequency components, and where the lowest frequency background and highest frequency noise are removed. This method is optimized using a simulated collection of parallel‐polarized and cross‐polarized Raman spectra of the enamel and then applied to a set of experimental data. The results show that the wavelet transform technique can extract the pure spectra from background and noise, with the depolarization ratio used to discriminate between early dental caries and sound enamel preserved. Copyright © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

Heuristic approach for peak regions estimation in gamma-ray spectra measured by a NaI detector

In this paper, a heuristic approach based on Slavic's peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectrum, we find it is simple and effective enough to be used together with the Statistics-sensitive Nonlinear Iterative Peak-Clipping method.     

Heuristic approach for peak regions estimation in gamma-ray spectra measured by a NaI detector

In this paper, a heuristic approach based on Slavic＇s peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectrum, we find it is simple and effective enough to be used together with the Statistics-sensitive Nonlinear Iterative Peak-Clipping method.     

波束域高分辨方位估计的方法、统计性能及水池实验结果

本文针对水声设备的实际应用，研究了波束域高分辨方位估计的MUSIC方法。首先分析了波束形成方法获得处理增益的原理，揭示了波束域高分辨方法具有较低分辨门限的机理；给出了波束域高分辨MUSIC算法，通过计算机仿真，比较了波束域和阵元域高分辨MUSIC法的统计性能，显示了波束域高分辨方法的优越性；进行了消声水池实验，结果表明波束域高分辨MUSIC法分辨力高，对阵列误差具有较大的宽容性。     

Analysis of experimental spectra andab initio calculations of water vapor

The results of ab initio calculations of water vapor absorption spectra obtained by Partridge and Schwenke are compared in detail with new experimental data. It is shown that the agreement between the calculated spectra of vibrational-rotational energy levels is better than Partridge and Schwenke pointed out in their pioneer paper, and the results of their calculations can be used directly for identification of lines in atmospheric spectra. At the same time, differences reaching 5cm ⁻¹ demonstrate that the potential energy function should be further refined. Institute of Atmospheric Optics of the SB RAS. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 93–101, March, 1999.