Ar Spectra Research Articles

Bi-LSTM fault diagnosis method for rolling bearings based on segmented interception AR spectrum analysis and information fusion

The rolling bearing fault diagnosis is affected by industrial environmental noise and other factors, leading to the existence of some redundant components after signal decomposition. At the same time, the existence of the modal aliasing phenomenon in empirical mode decomposition (EMD) and the relevant improved algorithms also leads to the existence of many invalid features in the components. These phenomena have great influence on the bearing fault diagnosis. So a rolling bearing bidirectional-long short term memory (Bi-LSTM) fault diagnosis method was proposed based on segmented interception auto regressive (SIAR) spectrum analysis and information fusion. The ensemble empirical mode decomposition (EEMD), the complementary ensemble empirical mode decomposition (CEEMD) and the robust EMD (REMD) algorithms decompose the rolling bearing fault signals, and AR spectrum analysis is performed on the obtained components respectively. By comparing the AR spectra of the components corresponding to different fault locations, the effective AR spectral values are intercepted as the eigenvalues of the data, and finally all the eigenvalues are fused to achieve the purpose of screening effective features more efficiently so as to reduce the impact of feature redundancy caused by mode aliasing on neural network training. Then the Bi-LSTM neural network was used as a rolling bearing fault diagnosis classifier, and the simulation experiments were conducted based on the rolling bearing fault signal data from Case Western Reserve University to verify the effectiveness of the proposed feature extraction and fault diagnosis method.

40Ar/39Ar dating of Paleoproterozoic shear zones in the Ellesmere–Devon crystalline terrane, Nunavut, Canadian Arctic

Paleoproterozoic gneisses of the Ellesmere–Devon crystalline terrane on southeastern Ellesmere Island are deformed by metre-scale, east-striking mylonite zones. The shear zones commonly offset pegmatitic dikes and represent the last episode of ductile deformation. Samples were dated by the 40Ar/39Ar step-heating method to put an upper limit on the time of deformation. Biotite from one tonalitic protolith and five shear zones give geologically meaningful results. Clusters of unoriented biotite grains pseudomorph granulite-facies orthopyroxene in some of the weakly deformed gneisses, whereas the shape-preferred orientation of biotite defines the mylonitic fabric. The intrusive age of the tonalitic protolith is 1958 ± 12 Ma, based on previous U–Pb dating of zircon. 40Ar/39Ar analysis of biotite from the same sample gave a plateau age of 1929 ± 23 Ma, which is interpreted as cooling from regional granulite facies metamorphism. Three nearby samples of mylonitic tonalite have 40Ar/39Ar ages in the range of ≈1870–1840 Ma. Biotite from two granitic mylonites over 80 km away return high-resolution Ar spectra in the same range, implying that widespread ductile shearing occurred at ≈1870–1840 Ma, or ≈90 million years after cooling from regional metamorphism. Although the 2.0–1.9 Ga gneisses of southeastern Ellesmere Island correlate with the Inglefield Mobile Belt in North-West Greenland and the Thelon Tectonic Zone, the late shear zones are superimposed on that juvenile arc long after the 1.97 Ga Thelon orogeny.

Progress of x-ray imaging crystal spectrometer utilizing double crystal assembly on KSTAR.

The x-ray imaging crystal spectrometer (XICS) for Korea Superconducting Tokamak Advanced Research (KSTAR) has been upgraded to increase its performance including measurement capabilities and stable operation. A dual crystal assembly for simultaneous measurements of the helium-like and hydrogen-like Ar spectra is successfully installed for improving measurement capabilities. Using a safety viewing port with an illuminator and removing the XICS control system from the harsh KSTAR tokamak hall for a stable operation are newly performed. The experimental results from the improved XICS are investigated.

버그 알고리즘을 이용한 청진음의 음향학적 분석법에 관한 연구

This study describes an acoustic analysis method of stethoscope signal using the Burg algorithm which is a kind of linear prediction, considering the heartsound production mechanism is linear and can be modelled by an inverse filter of the all-pole model. For this study, normal and heart diseased stethoscope sounds were collected in the pediatrics of an university hospital. The collected signals were preprocessed by noise filtering and analyzed by the Burg algorithm, a kind of linear prediction. The AR spectra and the formants for the heartsounds for the normal and the diseased children are estimated and the results are compared. The spectra showed outstanding differences in morphology and formant frequencies between the normal and the diseased children. Normal children showed relatively low frequency of F1(the first formant) and small negative slope from F1. VSD children revealed stiff slope change around F1 to F3. Spectra of ASD children is similar with the normal case, but have negative values of F3. F1-F2 difference of the functional murmur children were relatively large.

OES diagnostic of radicals in 33 MHz radio-frequency Ar/C2H5OH atmospheric pressure plasma jet

Ar/C2H5OH plasma jet is generated at atmospheric pressure by 33 MHz radio-frequency power source. This RF excitation frequencies which are higher than 13.56 MHz had rarely been used in atmospheric pressure plasma. The plasma characteristics of ethanol are investigated. The introduction of ethanol leads to the generation of four excited carbonaceous species C, CN, CH and C2 in plasma, respectively. Optical emission intensities of four carbonaceous species were strengthened with ethanol content increasing in the range of 0−4600 ppm. The ethanol content increase results in all the Ar spectra lines decrease. The reason is that the electron temperature decreases when ethanol content is high. The emission intensity ratios of C/C2, CN/C2 and CH/C2 decrease with the increase of ethanol content, showing that the relative amount of C2 is increasing by increasing the ethanol flow. The emission intensity ratios of excited species did not change much with the increase of RF power in stable discharge mode.

Radiative Characteristics of Reversed Polarity Gas-Puff Ar and Kr Plasmas

Experiments with regular and reversed polarities were carried out on the SHOTGUN-III Z-pinch device at Nihon University, Japan. SHOTGUN’s storage section consists of the 12- $\mu \text{F}$ fast capacitor bank, which was charged to 25 kV for these experiments and provided current up to 200 kA. The Ar and Kr gases were puffed between the electrodes through a hollow nozzle using a fast gas valve. Time-resolved X-ray detectors, time-integrated X-ray pinhole camera and two spectrometers, and an optical framing camera were applied for the study of radiative properties of Ar and Kr gas puffs. K-shell Ar spectra (3.9–4.2 A) and L-shell Kr spectra (6.3–7.6 A) show much intense He- and Li-like Ar and Ne- and Na-like Kr spectral features, respectively, and the evidence of the electron beams in reversed polarity experiments. The influence of reversed polarity on gas-puff plasma radiative characteristics and X-ray spectroscopic measurements is discussed. The advantages of using K-shell Ar and L-shell Kr for hot electron beam diagnostics are highlighted.

Prospects of X-ray imaging spectrometers for impurity transport: Recent results from the stellarator Wendelstein 7-X (invited).

This paper reports on the design and the performance of the recently upgraded X-ray imaging spectrometer systems, X-ray imaging crystal spectrometer and high resolution X-ray imaging spectrometer, installed at the optimized stellarator Wendelstein 7-X. High resolution spectra of highly ionized, He-like Si, Ar, Ti, and Fe as well as H-like Ar have been observed. A cross comparison of ion and electron temperature profiles derived from a spectral fit and tomographic inversion of Ar and Fe spectra shows a reasonable match with both the spectrometers. The also measured impurity density profiles of Ar and Fe have peaked densities at radial positions that are in qualitative agreement with the expectations from the He-like impurity fractional abundances, given the measured temperature profiles. Repeated measurements of impurity decay times have been demonstrated with an accuracy of 1 ms via injection of non-recycling Ti, Fe, and Mo impurities using a laser blow-off system.

Computational study of the electronic spectra of the rare gas fluorohydrides HRgF (Rg = Ar, Kr, Xe, Rn)

Simulation of the electronic spectra of HRgF (Rg = Ar, Kr, Xe, Rn) was carried out using the time-dependent density functional method, with the CAMB3LYP functional and several basis sets augmented with even-tempered diffuse functions. A full spectral assignment for the HRgF systems was done. The effect of the rare gas matrix on the HRgF (Rg = Ar and Kr) spectra was investigated and it was found that the matrix blue-shifted the spectra. Scalar relativistic effects on the spectra were also studied and it was found that while the excitation energies of HArF and HKrF were insignificantly affected by relativistic effects, most of the excitation energies of HXeF and HRnF were red-shifted. Spin–orbit coupling was found to significantly affect excitation energies in HRnF. Analysis of performance of the model core potential basis set relative to all-electron (AE) basis sets showed that the former basis set increased computational efficiency and gave results similar to those obtained with the AE basis set.

Proterozoic 40Ar/39Ar ages from cave deposits of the Malapa, Sterkfontein and Dinaledi fossil sites, Cradle of Humankind, South Africa

We have explored the use of 40 Ar / 39 Ar dating on Mn ooids and peloids, and fragments of indurated, extremely fine-grained mudstone occurring in cave sediments in the Cradle of Humankind (CoH) UNESCO world heritage site, to obtain ages of fossil-bearing cave sediments. Samples analysed were from the Malapa site (envisaged as a testing ground because it was previously dated with high precision by the uranium-lead method and paleomagnetism), the floor of the Dinaledi Chamber in Rising Star Cave, as well as boreholes 2 and 3 of the Sterkfontein Cave. The 40 Ar/ 39 Ar apparent ages of the dated samples turned out to be unrelated to cave formation processes, rendering the Malapa-based validation irrelevant. The results do, however, provide insight into aspects of the origin of the cave sediments and dated material. Most samples yielded disturbed 40 Ar/ 39 Ar spectra. The apparent pooled gas ages for the Mn ooids analysed from Malapa range between 476 ± 13 Ma and 1964 ± 13 Ma. Of 5 ooids from Sterkfontein, one yielded 1597 ± 13 Ma, while the rest range between 1960 ± 35 Ma and 2081 ± 13 Ma, the latter being a plateau age. Peloidal Mn nodules from Dinaledi Chamber samples yielded apparent ages between 1975 ± 9 Ma and 2096 ± 13 Ma. Indurated mudstone fragments were analysed from Sterkfontein and for 3 out of 4 samples, the apparent pooled gas ages range from 1970 ± 14 Ma to 2059 ± 13 Ma (one yielded 1623 ± 15 Ma). We conclude that ooids, peloids and indurated mudstone fragments are derived from higher levels in the Transvaal Supergroup stratigraphy, trapped in karst features over time as these were eroded, and finally washed into the caves.

Visible photodissociation spectra of gaseous rhodamine ions: Effects of temperature and tagging

This paper reports on the effect of He, Ar, and N2 tagging on visible photodissociation (VisPD) spectra of Rhodamine 123 ions. We show that the effect of tagging on the determination of the 0–0 transition in the electronic spectra is negligible. In contrast to the photodissociation spectra of the bare ions, the tagging method provides resolved Franck-Condon envelopes. Ar and N2 tagging spectra revealed minor blue-shifts (∼ 0.5nm) for some maxima in the Franck-Condon envelope with respect to the He tagging spectrum. The N2 tagging VisPD spectrum was less resolved compared to He and Ar tagging spectra. Further, we have investigated the effect of temperature on photodissociation spectra of bare rhodamine ions. At room temperature, the absorption spectrum is dominated by the absorption of vibrationally excited ions. Vibrationally relaxed ions start to be dominantly sampled at about 150K. In average, three to four photons are required to induce photodissociation of the rhodamine ions and it is slightly wavelength dependent. We ascribe it to the fluorescence process.

A spectrophotometric method for determination of the optical constants of materials

We propose a method for determining the optical constants of materials used in transmission optics. This technique is based on correction of absorption spectra. The absorption A may be divided into two parts: AT describes the contribution of absorption to the transmission spectrum, and AR describes the contribution of absorption to the reflection spectrum. The AT and AR spectra used to correct the RT spectra were calculated using correction functions and the total absorption A. Correction removes absorption from the spectra, so that the existing methods for determining the refractive index n can be used. We obtain analytical expressions for the absorption coefficient α and assess the accuracy of the method; this assessment indicated that spectral correction enables n to be determined to a maximum accuracy of 0.0001. The method was tested on optical silicon near the 9-μm absorption band.

Atmospheric pressure plasma polymerization using double grounded electrodes with He/Ar mixture

In this study, we have proposed the double grounded atmospheric pressure plasma jet (2G-APPJ) device to individually control the plasmas in both fragmentation (or active) and recombination (or passive) regions with a mixture of He and Ar gases to deposit organic thin films on glass or Si substrates. Plasma polymerization of acetone has been successfully deposited using a highly energetic and high-density 2G-APPJ and confirmed by scanning electron microscopy (SEM). Plasma composition was measured by optical emission spectroscopy (OES). In addition to a large number of Ar and He spectra lines, we observed some spectra of C2 and CH species for fragmentation and N2 (second positive band) species for recombination. The experimental results confirm that the Ar gas is identified as a key factor for facilitating fragmentation of acetone, whereas the He gas helps the plume of plasma reach the substrate on the 2nd grounded electrode during the plasma polymerization process. The high quality plasma polymerized thin films and nanoparticles can be obtained by the proposed 2G-APPJ device using dual gases.

Upgrades of imaging x-ray crystal spectrometers for high-resolution and high-temperature plasma diagnostics on EAST.

Upgrade of the imaging X-ray crystal spectrometers continues in order to fulfill the high-performance diagnostics requirements on EAST. For the tangential spectrometer, a new large pixelated two-dimensional detector was deployed on tokamaks for time-resolved X-ray imaging. This vacuum-compatible detector has an area of 83.8 × 325.3 mm(2), a framing rate over 150 Hz, and water-cooling capability for long-pulse discharges. To effectively extend the temperature limit, a double-crystal assembly was designed to replace the previous single crystals for He-like argon line measurement. The tangential spectrometer employed two crystal slices attached to a common substrate and part of He- and H-like Ar spectra could be recorded on the same detector when crystals were chosen to have similar Bragg angles. This setup cannot only extend the measurable Te up to 10 keV in the core region, but also extend the spatial coverage since He-like argon ions will be present in the outer plasma region. Similarly, crystal slices for He-like iron and argon spectra were adopted on the poloidal spectrometer. Wavelength calibration for absolute rotation velocity measurement will be studied using cadmium characteristic L-shell X-ray lines excited by plasma radiation. A Cd foil is placed before the crystal and can be inserted and retracted for in situ wavelength calibration. The Geant4 code was used to estimate X-ray fluorescence yield and optimize the thickness of the foil.

Deposition of Polymer Thin Film Using an Atmospheric Pressure Micro-Plasma Driven by Dual-Frequency Excitation

Polymer thin film deposition using an atmospheric pressure micro-plasma jet driven by dual-frequency excitations is described in this paper. The discharge process was operated with a mixture of argon (6 slm) and a small amount of acetone (0-2100 ppm). Plasma composition was measured by optical emission spectroscopy (OES). In addition to a large number of Ar spectra lines, we observed some spectra of C, CN, CH and C2. Through changing acetone content mixed in argon, we found that the optimum discharge condition for deposition can be characterized by the maximum concentration of carbonaceous species. The deposited film was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The XPS indicated that the film was mostly composed of C with trace amount of O and N elements. The FTIR suggested different carbon-containing bonds (−CHx, C=O, C=C, C-O-C) presented in the deposited film.

Crustal exhumation of the Western Gneiss Region UHP terrane, Norway: 40Ar/39Ar thermochronology and fault-slip analysis

article i nfo Ar/ 39 Ar muscovite thermochronology 40 Ar/ 39 Ar K-feldspar thermochronology Fault-slip analysis New 40 Ar/ 39 Ar muscovite and K-feldspar thermochronology combined with existing data reveal the timing and patterns of late-stage exhumation across the Western Gneiss Region (U)HP terrane. Muscovite age contours show that exhumation into the mid-upper crust progressed westward over a ~20 Myr period (~400-380 Ma). This exhumation was caused by i) E-W stretching and eastward tilting north of Nordfjord, where muscovite ages decrease from the foreland allochthons westward into the UHP domains, and ii) differential exhumation south of Nordfjord, where muscovite ages depict a NE-SW dome-like pattern and the Western Gneiss Region is bounded by overlying units little affected by the Scandian metamorphism. Exhumation of the UHP domains into the mid-upper crust by late folding continued through ~374 Ma. The smooth gradient of fairly flat muscovite age spectra demonstrates minimal influence of excess Ar, which is relatively unusual for a (U)HP terrane. 40 Ar/ 39 Ar spectra and modeled cooling histories from K-feldspar combined with brittle-ductile

The energy of waves in the photosphere and lower chromosphere

Most static 1D atmosphere models in the quiet Sun predict a rise of the gas temperature at chromospheric layers, but numerical simulations only yield an increase in the brightness temperature. We investigate the thermal structure in the solar chromosphere as derived from an LTE inversion of Ca II H spectra in QS and active regions. We investigate the temperature stratifications on differences between magnetic and field-free regions in the QS, and between QS and ARs. We determine the energy content of individual calcium bright grains (BGs). The rms temperature fluctuations are below 100 K in the photosphere and 200-300 K in the chromosphere. The average temperature stratification in the QS does not exhibit a clear chromospheric temperature rise, opposite to the AR case. We find an energy content of about 7*10E18 J for BGs that repeat with a cadence of about 160 secs. The precursors of BGs have a vertical extent of about 200 km and a horizontal extent of about 1 Mm. The comparison of observed with synthetic NLTE profiles confirms that the solar chromosphere in the QS oscillates between an atmosphere in radiative equilibrium and one with a moderate chromospheric temperature rise. Two-dimensional x-z temperature maps exhibit nearly horizontal canopy-like structures with a few Mm extent around photospheric magnetic field concentrations at a height of about 600 km. The large difference between QS regions and ARs, and the better match of AR and non-LTE reference spectra suggest that magnetic heating processes are more important than commonly assumed. The temperature fluctuations in QS derived by the LTE inversion do not suffice on average to maintain a stationary chromospheric temperature rise. The spatially and vertically resolved information on the temperature structure allows one to investigate in detail the topology and evolution of the thermal structure in the lower solar atmosphere.

IR low-temperature matrix, X-ray and ab initio study on l-isoserine conformations

The IR low-temperature Ar and Kr matrix spectra of l-isoserine were registered for the first time and interpreted by means of the anharmonic DFT frequencies calculated at the B3LYP/aug-cc-pVTZ and B3LYP/aug-cc-pVDZ levels. 54 l-isoserine conformers were predicted to be stable at the B3LYP/aug-cc-pVDZ level. Population of the 8 most stable conformers was based on the QCISD/aug-cc-pVDZ energies, corrected for thermal anharmonic factors obtained at the B3LYP/aug-cc-pVDZ level. We found several conformers to be present in the measured matrices and conformer 1 to be dominating. Presence of the conformer 2 is well confirmed by the nu(C=O) band at 1790 cm(-1) and two bands at 1380 and 1350 cm(-1). Presence of the conformer 4 is quite well confirmed by the nu(C-O) bands at 1120 and 1095 cm(-1). Slightly weaker arguments are found for the observation of conformers 6 and 3. Calculations on 54 neutral and 5 zwitterionic conformers in water at the IEF-PCM/B3LYP/aug-cc-pVDZ level suggest that one neutral and one zwitterionic conformer co-exist in the aqueous environment. The crystal structure of l-isoserine was solved by X-ray diffraction analysis. The compound crystallizes without solvent in the chiral P2(1)2(1)2 space group. The asymmetric unit contains a single molecule. The molecule is in its zwitterionic form with the CH(2)-NH(3) side chain in the gauche conformation with respect to the hydroxyl group and in the anti conformation with respect to the carboxylate group. The structure of l-isoserine is dominated by a set of intermolecular hydrogen bonds. The strongest one appears between the OH and COOH groups of two neighbouring molecules: the O...H contact is of 1.66(2) A, which is amongst the shortest H-bonds of this kind observed in amino acid crystal structures.

40 Ar/ 39 Ar dating of synkinematic white mica: insights from fluid-rock reaction in low-grade shear zones (Mont Blanc Massif) and constraints on timing of deformation in the NW external Alps

Abstract This paper highlights the use of synkinematic white mica, biotite and phlogopite for the dating of deformation in ductile shear zones within crystalline rocks under low-grade metamorphic conditions. The Mont Blanc shear zones range from 1 mm to 50 m in width and have localized intense fluid flow, resulting in substantial differences in mineralogy and whole-rock geochemistry. On the basis of their synkinematic alteration assemblages and geographic distribution within the Mont Blanc Massif, three main metamorphic zones are distinguished within the network of shear zones. These are: (i) epidote±white mica-bearing assemblages; (ii) chlorite–phlogopite-bearing assemblages; and (iii) white mica±biotite±calcite±actinolite±epidote- bearing assemblages. 40 Ar/ 39 Ar age spectra of biotite and phlogopite are complex, and reflect significant variations in chemical composition. In biotite, this is partly due to inheritance from precursor Variscan magmatic biotite. In contrast, new white mica grew at the expense of feldspar during Alpine deformation and its Ar spectra do not show any excess 40 Ar. On the SE side of Mont Blanc, ages of shear zone phengites have a narrow range of 15.8–16.0±0.2 Ma, which is in the same age range as 40 Ar/ 39 Ar ages of minerals from kinematically related veins. The top-to-SE sense of shear is consistent with initiation of a Mont Blanc flower-structure within a dextral transpressional system by 16 Ma. On the NW side, mini-plateaux ages of 14.5±0.3 and 23.4±0.4 Ma are preserved in the same sample, suggesting the possibility of two phases of deformation. This is also supported by partly preserved ages of 18–36.6 Ma in biotites and phlogopites. Ages between 36 and 18 Ma might reflect ongoing top-to-NW thrusting, following Penninic Front activation, in a context of nappe stacking and crustal thickening. NW-directed thrusting on the NW side of Mont Blanc continued after 18 Ma, synchronous with SE-directed thrusting on the SE side of the massif. These divergent movements produced the overall pop-up geometry of the Mont Blanc Massif, which may correspond to a positive flower structure developed within a zone of regional dextral transpression extending SW from the Rhone valley into the Mont Blanc area.

Recovering of autoregressive spectral estimates of signals buried in noise

In this paper, we propose a noise modeling that does not destroy AR structure of buried signals in noise independently of its nature (white or colored, Gaussian or not) and its variance. Expression of perturbed AR coefficients is derived and proposed restoration does not use any a-priori information on the nature of noise and its variance. It is shown that AR coefficients are closer to nominal ones (noise-free) in the presence of noise for lower frequency contents with respect to the sampling frequency of corresponding continuous-time processes from which samples are taken for AR estimation. For unknown frequency contents, denoising of AR coefficients is obtained by decreasing the time interval separating samples used by AR estimation. A model order selection adapted to degraded signal-to-noise ratios is proposed. Performances of the proposed recovering of original AR spectra are demonstrated via signals buried in white and colored noise. Observed results are in accordance with the developed theory.

Fermi-shuttle processes in the electron emission by ion impact: Contribution to radiation damages

Secondary electrons, formed in biological tissues by high-energy particle impact, significantly contribute to the fragmentation of small molecules and to single- and double-strand brakes in DNA. Differential spectra of electrons emitted in the collisions of decelerating swift ions are of vital importance for estimating ion impact radiation damages. We demonstrate that the so-called Fermi-shuttle-type acceleration mechanism can produce a significant enhancement in the emission of high-energy secondary electrons. Double differential cross-sections for electron emission, measured in the collisions of N + and N 2 + ions with Ar targets at 750 keV/ u impact energy, clearly show this effect. The measured cross-sections are in good agreement with the theoretical results of CTMC calculations. Multiple scattering contribution to the Ar spectra above 300 eV is proved to be significant.