The Method of Virtual Experts in Mathematical Diagnostics

Mathematical Diagnostics (MD) deals with identification problems arising in different practical areas. Some of these problems can be described by mathematical models where it is required to identify points belonging to two or more sets of points. Most of the existing tools provide some identification rule (a classifier) by means of which a given point is assigned (attributed) to one of the given sets. Each classifier can be viewed as a virtual expert. If there exist several classifiers (experts), the problem of evaluation of experts’ conclusions arises. In the paper for the case of supervised classification the method of virtual experts (the VE-method) is described. Based on this method, a generalized VE method is proposed where each of the classifiers can be chosen from a given family of classifiers. As a result, a new optimization problem with a discontinuous functional is stated. Examples illustrating the proposed approach are provided. The work of the second author was supported by the Russian Foundation for Fundamental Studies (RFFI) under Grant No 03-01-00668.     

衍射辐射及其在电子束诊断中的应用

衍射辐射是由于运动的带电粒子遇到随空间变化的电介质而由感应电流产生的一种辐射. 衍射辐射由于其非阻拦性, 多参数性, 可在线性, 非常适合下一代对撞机和第四代光源的电子束诊断. 简要介绍了其物理机制, 系统的讨论了其在电子束诊断中的应用.     

Measurements and inverse calculations of spectral radiation intensities of a turbulent ethylene/air jet flame

Fast (6250 Hz) line-of-sight measurements of infrared spectral radiation intensities (I_λ) from a luminous flame and a new deconvolution technique for the estimate of local scalar properties using inverse radiation calculations are reported. Time series data of I_λ for one diametric and nine chord-like radiation paths in a representative horizontal plane were measured. Statistical properties of I_λ, including mean, root mean square (rms), probability density function, autocorrelation coefficient, and power spectral density, were obtained from the time series data. The measured statistical properties of I_λ at two representative wavelengths, which are dominated by carbon dioxide (CO₂) and soot radiation, respectively, are reported. The autocorrelation coefficient data show large negative loops with repeatable zero crossings at 20 ms and minimum values as low as −0.2 at 30–40 ms. Radial distributions of mean and rms CO₂ mole fractions and temperatures were estimated using inverse calculations of mean I_λ at two different wavelengths dominated by CO₂ radiation in conjunction with the relationship of these quantities to mixture fractions. Soot volume fraction distributions were also estimated using inverse calculations of mean I_λ at a wavelength dominated by continuum soot radiation. The estimated local mixture fraction distributions were in reasonably good agreement with sampling data from similar flames. The calculated mean I_λ from 1.4 to 4.8 μm other than those used in the inverse calculations matched the experimental data well. The present method provides non-intrusive measurements of major gas species and temperature statistics in turbulent soot containing flames not accessible to other optical diagnostics.     

Approaches to uncertainty evaluation based on proficiency testing schemes in chemical measurements

Since the advent of the Guide to the Expression of Uncertainty in Measurement (GUM) founding the principles of uncertainty evaluation, numerous projects have been carried out to develop alternative practical methods when it is impossible to model technical or economical aspects of the measurement process. These methods can use all the experimental data available to the laboratories, such as repeatability, reproducibility, quality-control charts, etc. The studies presented in this paper compare the results obtained by the modelling method from GUM with the uncertainties found by applying alternative methods. They show two examples, one in the field of environmental monitoring, the other in the biomedical field, based on the exploitation of PT schemes results. Presented at BERM-11, October 2007, Tsukuba, Japan.     

利用发射光谱进行常压介质阻挡放电等离子体诊断及其在材料表面改性上的应用(英文)

使用介质阻挡放电光谱诊断装置,对常压介质阻挡放电在材料改性过程中的等离子体发射光谱进行测量,记录和比较了空气、氦气和氩气常压介质阻挡放电等离子体发射光谱,并运用氩元素谱线的相对强度来诊断电子温度等物理参量,以达到对材料表面改性过程的实时监控。工作的结果对常压介质阻挡放电及其在材料改性上的应用具有重要的意义     

The first measured Ag I, Ag II and Ag III Stark broadening parameters

The Stark widths (W) and shifts (d) of two neutral (520.908 and 546.550 nm), eleven singly (211.382, 224.643, 224.874, 232.029, 232.468, 233.140, 241.141, 241.323, 243.781, 244.793 and 276.754 nm) and three doubly (216.189, 231.004 and 239.569 nm) ionized silver (Ag I, Ag II and Ag III, respectively) spectral lines have been measured in nitrogen plasma at about 18,000 K electron temperature and electron density ranged between 0.65 × 10²³ and 1.15 × 10²³ m^− 3. They are the first measured W and d values while those of the Ag II and Ag III lines are the first published data in these spectra. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in nitrogen with silver atoms, as impurities, evaporated from silver cylindrical plates located in the homogeneous part of the discharge. No theoretical predictions exist for W and d values of above mentioned spectral lines. Besides, we have checked the transition probability ratio of two investigated Ag I lines. An agreement with theoretical predictions was found.     

Prediction of temperature-insensitive molecular absorption lines in laser-assisted combustion diagnostics

In laser-assisted combustion diagnostics it is a recurring task to predict molecular transitions whose signal strength depends only weakly on variations in temperature. The signal strength is proportional to the Boltzmann fraction of the level probed and the amplitude of the absorption line profile. In the past investigations have been presented in which this task was attack by detailed numerical calculations of the temperature dependence of pertinent physical properties of the molecule. Another widely applied approach relies on an analytical formula for the Boltzmann fraction of hetero-nuclear diatomic molecules and the neglect of line shape effects. The analytical approach experiences a continuing popularity in laser-assisted combustion diagnostics, which is why we compared both approaches with each other. The objective of this comparison was to assess the accuracy of the analytical approach and to reveal its potential pitfalls. Our comparison revealed that the analytical approach suffers from mediocre accuracy, which makes it unfit for practical applications. One cause is the neglect of higher lying vibrational levels, which show a non-negligible population for typical flame temperatures. Another reason is the neglect of fine structure splitting in molecules with non-zero orbit angular momentum in the ground state. Another reason for the observed inaccuracy is the neglect of line shape effects quenching, which were found to have a significant effect on the temperature sensitivity of a line. Because of its insufficient accuracy due to both oversimplified models of the molecular energy levels and the neglect of line shape effects and quenching we discourage from applying the analytical approach and recommend the use of detailed numerical approaches that are free of the above limitations.     

广义线性模型(六)

本讲座是广义线性模型这个题目的一个比较系统的介绍。主要分 3部分 :建模、统计分析与模型选择和诊断。写作时依据的主要参考资料是L .Fahrmeir等人的 :《MultivariateStatisticalModel ingBasedonGeneralizedLinearModles》。     

Synthesis of Bioactive and Porous Organic-Inorganic Hybrids for Biomedical Applications

Bioactivity has been exhibited by a limited range of ceramics since the invention of Bioglass®. Recently, some bioactive polymeric organic-inorganic hybrids were introduced, including not only organically modified silicates (Ormosils) synthesized from polydimethylsiloxane (PDMS) and tetraethoxysilane but also those with gelatin and 3-glycidoxypropyl-tremethoxysilane. Preparation of the bulk and porous hybrids and their polymeric structures analyzed by Si NMR spectroscopy were presented. In vitro bioactivity or apatite deposition in a simulated body fluid of the Kokubo recipe were also described for those hybrids. Freeze-drying techniques introduced porosity (up to 90%) and pores extending in a preferred direction.     

Characterizing the coating and size-resolved oxidative stability of carbon-coated aluminum nanoparticles by single-particle mass-spectrometry

Aluminum nanoparticles are of significant interest in enhancing the rate of energy release from propellants. One of the major impediments to their use is that bare aluminum is highly reactive, while oxide coated aluminum significantly decreases overall performance. We investigate creating aluminum nanoparticles with a thin carbon coating using either a laser induced plasma or a DC plasma-arc. The carbon coating was created by injecting ethylene (C₂H₄) directly downstream of the plasma. The elemental composition of the coated aluminum nanoparticles was measured in real time with a recently developed quantitative single particle mass spectrometer (SPMS). We found that the aluminum nanoparticles were coated with a carbon layer of thickness around 1–3 nm.The thermal and oxidative stability of these particles was determined by passing the aerosols through a heated flow reactor in a carrier flow of either air or argon, and measuring the aluminum, carbon and oxygen content in the particles with the single particle mass spectrometer. We found that below 700°C the coating was stable, but that the coating oxidized above ∼ ∼800°C. In contrast the carbon coating was thermally stable above ∼ ∼900°C. These results indicate that a carbon coating may be a suitable passivating agent.