Влияние добавок благородных металлов на газочувствительные свойства оксида вольфрама, полученного золь-гель методом

The effect of Pd and Ag additives (0,5-1,5 % by weight) on the crystal structure and gas sensitivity of tungsten oxide WO3 prepared by sol-gel method, has been studied. A large increase (more than 3-4 times) of the sensitivity to CO and CH4 as compared with the starting WO3, and the shift of the high sensitivity band to low temperatures (from 120 °C) have been established. Response values to 300 ppm CO and 9,8 ppm CH4 in the air have been 350 and 320 %, respectively (170 °C).Оценено воздействие 1,5 мас.% добавок Pd и Ag на изменение структуры и газовой чувствительности WO3, полученного золь-гель методом. Установлено существенное (более чем в 3-4 раза) возрастание чувствительности к СО и СН4 по сравнению с исходным WO3, а также смещение интервала высокой чувствительности в область более низких температур (от 120 °С). Величина отклика к 3000 ppm ТО и 9,8 ppm СН4 в воздухе составляла до 350 и 320 % соответственно (170 °С)

Физико-химические свойства композиции WO3-Co3O4, полученной золь-гель методом

Tungsten oxide WO3, cobalt oxide Co3O4 and their compositions prepared by the sol-gel method, have been characterized by X-ray diffraction (XRD), IR-spectroscopy, scanning electron microscopy (SEM), thermogravimetric and differential thermal analysis (TG-DTA). The formation of heterogeneous material consisting mainly of CoWO4 in the process of joint annealing of oxides has been established. It has been observed that the mixed composition is much more sensitive to nitrogen dioxide (2 ppm) than the starting material, WO3.Методами РФА, ИК-спектроскопии, сканирующей электронной микроскопии, ТГ-ДТА изучено формирование кристаллической структуры оксида вольфрама WO3, оксида кобальта Co3O4, полученных золь-гель методом, и их композиций. Установлено образование в процессе совместного отжига оксидов гетерогенного материала с преобладанием фазы СоWО4, а также существенное возрастание чувствительности смешанной композиции к 2 ppm диоксида азота по сравнению с исходным WO3

Газочувствительная композиция оксида вольфрама с многостенными углеродными нанотрубками

Multiwall carbon nanotubes (MWCNTs), exhibiting high gas adsorption activity, have been prepared in the high voltage discharge plasma under atmospheric pressure from a mixture of hydrocarbons (methane, propane) and air. The structural characteristics of nanotubes have been studied by TEM. Composition WO3 - MWNTs, prepared by sol-gel method, is of interest to create selective sensitive detectors of combustible gases. The greatest sensitivity to propane (≤ 500 %) has been observed at the substrate temperature below 200 °C, whereas high sensitivity to NO2 (≤300 %) has been observed at higher temperatures (T - 240 °C and more).Получена газочувствительная композиция оксида вольфрама с многостенными углеродными нанотрубками (WO3 - МУНТ), представляющая интерес для создания селективных чувствительных датчиков горючих газов. Изготовлены и испытаны микромощные сенсоры (P ≤ 85 мВт), содержащие WO3 - МУНТ в качестве чувствительного элемента. Наибольшая чувствительность к пропану ( ≤ 500 %) наблюдается при температуре подложки менее 200 ˚С, в то время как заметная чувствительность к NO2 ( ≤ 300 %) наблюдается при более высоких температурах (T ≈ 240 ˚С и выше)

Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation

In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X

Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events

Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors

Globally, songs and instrumental melodies are slower and higher and use more stable pitches than speech: A Registered Report

Both music and language are found in all known human societies, yet no studies have compared similarities and differences between song, speech, and instrumental music on a global scale. In this Registered Report, we analyzed two global datasets: (i) 300 annotated audio recordings representing matched sets of traditional songs, recited lyrics, conversational speech, and instrumental melodies from our 75 coauthors speaking 55 languages; and (ii) 418 previously published adult-directed song and speech recordings from 209 individuals speaking 16 languages. Of our six preregistered predictions, five were strongly supported: Relative to speech, songs use (i) higher pitch, (ii) slower temporal rate, and (iii) more stable pitches, while both songs and speech used similar (iv) pitch interval size and (v) timbral brightness. Exploratory analyses suggest that features vary along a “musi-linguistic” continuum when including instrumental melodies and recited lyrics. Our study provides strong empirical evidence of cross-cultural regularities in music and speech

Magnetic configuration effects on the Wendelstein 7-X stellarator

The two leading concepts for confining high-temperature fusion plasmas are the tokamak and the stellarator. Tokamaks are rotationally symmetric and use a large plasma current to achieve confinement, whereas stellarators are non-axisymmetric and employ three-dimensionally shaped magnetic field coils to twist the field and confine the plasma. As a result, the magnetic field of a stellarator needs to be carefully designed to minimize the collisional transport arising from poorly confined particle orbits, which would otherwise cause excessive power losses at high plasma temperatures. In addition, this type of transport leads to the appearance of a net toroidal plasma current, the so-called bootstrap current. Here, we analyse results from the first experimental campaign of the Wendelstein 7-X stellarator, showing that its magnetic-field design allows good control of bootstrap currents and collisional transport. The energy confinement time is among the best ever achieved in stellarators, both in absolute figures (τE > 100 ms) and relative to the stellarator confinement scaling. The bootstrap current responds as predicted to changes in the magnetic mirror ratio. These initial experiments confirm several theoretically predicted properties of Wendelstein 7-X plasmas, and already indicate consistency with optimization measures

Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X

The next step in the Wendelstein stellarator line is the large superconducting device Wendelstein 7-X, currently under construction in Greifswald, Germany. Steady-state operation is an intrinsic feature of stellarators, and one key element of the Wendelstein 7-X mission is to demonstrate steady-state operation under plasma conditions relevant for a fusion power plant. Steady-state operation of a fusion device, on the one hand, requires the implementation of special technologies, giving rise to technical challenges during the design, fabrication and assembly of such a device. On the other hand, also the physics development of steady-state operation at high plasma performance poses a challenge and careful preparation. The electron cyclotron resonance heating system, diagnostics, experiment control and data acquisition are prepared for plasma operation lasting 30 min. This requires many new technological approaches for plasma heating and diagnostics as well as new concepts for experiment control and data acquisition