The full complex of 18 fundamental optical functions describing a barium selenide crystal was obtained in the spectral range of 0–40 eV. Their main features and general laws were established. ...Calculations were performed using a series of computer programs based on the Kramers–Kronig integral relations, the Taft–Philippe extrapolation model, and experimental reflectance spectra in the regions of 3.0–5.5 eV at 2 K and 3–40 eV at 77 K.
The spectral dependences of the imaginary parts of the dielectric permittivity ε
2
(E), bulk (–Im ε
–1
) and surface (–Im (1 + ε)
–1
) characteristic electron energy losses for a barium selenide ...crystal are decomposed into 34 elementary bands in the 3–5.5 eV region at 2 K and in the 5.5–26 eV region at 77 K by an improved combined Argand diagram method. For each band in the three types of spectra, we determined the energy maxima E
i
, the half-widths H
i
, the amplitudes I
i
, the areas S
i
, and the oscillator strengths f
i
. The parameter f
i
is calculated using a modification of the familiar formula for the effective number of valence electrons n
eff
(E). We have established the main features of the 34 elementary bands of barium selenide in the 3–26 eV region, due to excitons and transverse and longitudinal interband transitions.
Spectra of 11 optical functions of CaO in the ranges 6.5–7.2 eV at 2 K and 0–60 eV at 77 K were determined. A total of 14 maxima and shoulders of excitons and interband transitions were found ...including two distinct exciton structures at 6.9 and 11.4 eV and volume and surface plasmon maxima at ~38.3 and 33.2 eV, respectively. Their principal features and general trends were established. Variable formation efficiencies of spectra of the dielectric permittivity and characteristic electron-energy losses in different spectral ranges were analyzed. The calculations used known experimental reflectance spectra and computer programs based on the Kramers–Kronig correlations and analytical formulae for the relationship between optical functions.
Integral spectra of the imaginary parts of the dielectric permittivity ε
2
(E) and characteristic volume (–Im ε
–1
) and surface –Im (1 + ε)
–1
energy losses of calcium oxide were deconvoluted into ...elementary components in the range 6–40 eV. The main component parameters including the energies of maxima and oscillator strengths were determined using an improved non-parametric method of united Argand diagrams and the method of the effective number of valence electrons participating in the transitions. A total of 41 components with oscillator strengths in the range 0.001–0.22 were identified instead of the 14 maxima and shoulders of the integral spectra. They were caused by transverse and longitudinal exciton and interband transitions.
The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared ...spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm
−1
. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described.
The concept of planetary rolling dates back to the Nineteenth Century. However, it wasn't until the end of the 1940s that first prototypes of planetary mills for rolling strip and sheet were ...developed and placed in operation. All of the research in this field was focused on the behavior of the metal in the deformation zone during the rolling of the semifinished products in the mills. The further progress of planetary-mill design proceeded in two directions, which differed in the type of work rolls used: rolls with a smooth cylindrical body and rolls with a pass of variable profile. This difference accounts for both the design differences between the mills and the technological characteristics of the rolling operation and finished product. We will take a detailed look at the process of obtaining a rolled product by converting a square semifinished product into a finished square. We will also determine the area of contact of the metal with the work roll and the separating force acting on the roll in planetary section mills.
The vertical coupling of the stratosphere‐mesosphere system through quasi‐stationary and traveling planetary waves during the major sudden stratospheric warming (SSW) in the Arctic winter of ...2003/2004 has been studied using three types of data. The UK Met Office (UKMO) assimilated data set was used to examine the features of the global‐scale planetary disturbances present in the winter stratosphere of the Northern Hemisphere. Sounding the Atmosphere using Broadband Emission Radiometry (SABER) satellite measurements were used as well for extracting the stationary planetary waves in the zonal and meridional winds of the stratosphere and mesosphere. Radar measurements at eight stations, four of them situated at high latitudes (63–69°N) and the other four at midlatitudes (52–55°N) were used to determine planetary waves in the mesosphere‐lower thermosphere (MLT). The basic results show that prior to the SSW, the stratosphere‐mesosphere system was dominated by an upward and westward propagating ∼16‐day wave detected simultaneously in the UKMO and MLT zonal and meridional wind data. After the onset of the SSW, longer‐period (∼22–24 days) oscillations were observed in the zonal and meridional MLT winds. These likely include the upward propagation of stationary planetary waves from below and in situ generation of disturbances by the dissipation and breaking of gravity waves filtered by stratospheric winds.
We have estimated temperatures from meteor radar measurements using the gradient method and the full width at half maximum method over Kazan (56°N 49°E) and Collm (51°N, 13°E). The time series cover ...the period 2016–2019. The temperature gradient model is constructed from SABER temperature observations. We demonstrate that annual mean, amplitudes and phases of the annual and semiannual oscillations of the radar temperatures are close to those of the MLS and SABER temperatures. The annual mean temperatures over Kazan and Collm differ non-significantly. The seasonal variability of the radar temperature is mostly due to the annual cycle which tends to grow with latitude. The gradient method produces temperatures which agree with the SABER temperatures better than with the MLS ones. The harmonics of the annual oscillations from periods of 73 days up to periods of about 40 days are the most significant day-to-day temperature oscillations and have zonal wavenumber zero. Their periods and phases are in good correspondence with those of the MLS and SABER ones. We also show some results which demonstrate that at 56°N the FWHM method is not as robust as the gradient method.
Different problems may occur during acid treatment of oil reservoirs because of the incompatibility of acid with rocks and fluids. One of the issues is the formation of acid-in-oil emulsions, which ...block pore throats and hinder acid removal. The standard "bottle-test" method does not fully characterize such emulsions and allows only quick reagent selection. This article presents a new methodology that enables the evaluation of emulsion formation and the possible risk for acid treatment. This methodology includes visual control and measurement of viscosity, interfacial tension, and voltage stability. We found that HCl-based emulsions are generally more viscous, finer, and stable, but the high strength of the acid may lead to emulsion breakdown. We also established that emulsions that are stable under static conditions may break down after applying mechanical stress, which is a characteristic of sulfamic acid-based emulsions. Although it may not be possible to separate emulsions visually, a water content gradient may be observed in an emulsion column. Our results demonstrate that the acid and oil parameters are interconnected in emulsion formation issues. This methodology and the obtained results may be applied for quick and proper reagent selection for better acid treatment results.
The paper considers the development of an eco-friendly acidic composition for treating high-temperature carbonate reservoirs. The nontoxic, high-boiling glycolic acid and eco-friendly additive ...components makes this composition suitable for treating geothermal wells that comprise a clean energy source.
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