This paper contains a description of the most recent version of the hydrometeor classification algorithm for polarimetric Weather Surveillance Radar-1988 Doppler (WSR-88D). This version contains ...several modifications and refinements of the previous echo classification algorithm based on the principles of fuzzy logic. These modifications include the estimation of confidence factors that characterize the possible impacts of all error sources on radar measurements, the assignment of the matrix of weights that characterizes the classification power of each variable with respect to every class of radar echo, and the implementation of a class designation system based on the distance from the radar and the parameters of the melting layer that are determined as functions of azimuth with polarimetric radar measurements. These additions provide considerable flexibility and improve the discrimination between liquid and frozen hydrometeors. The new classification scheme utilizes all available polarimetric variables and discerns 10 different classes of radar echoes. Furthermore, a methodology for the new fuzzy logic classification scheme is discussed and the results are illustrated using polarimetric radar data collected with the Norman, Oklahoma (KOUN), WSR-88D prototype radar during a mesoscale convective system event on 13 May 2005.
The results of four experiments on studying preliminarily statically compressed gaseous helium and deuterium during their subsequent compression in explosive spherical cascade structures providing ...quasi-isentropic gas compression are presented. For helium, the following parameters were achieved: in one experiment, the compression pressure is
P
mean
≈ 4.9 TPa at a density ρ
max
≈ 6.4 g/cm
3
and the compression ratio is δ = ρ/ρ
0
≈ 320; in another experiment,
P
mean
≈ 10.9 TPa, ρ
max
≈ 10.3 g/cm
3
, and δ ≈ 470. For deuterium, these parameters are
P
mean
≈ 3.4 TPa, ρ
max
≈ 6.0 g/cm
3
, and δ ≈ 162 in one experiment and
P
mean
≈ 13.3 TPa, ρ
max
≈ 11.4 g/cm
3
, and δ ≈ 520 in another experiment. The gas density was determined by an X-ray method using the position of the boundaries of the steel shells compressing a gas. The experiments are simulated with a one-dimensional gasdynamic software package, in which the Kopyshev–Khrustalev equations of state are used for the gases under study. The pressures are determined using calculations, in which the dynamics of gas compression is satisfactorily simulated for the entire set of experiments.
We present our experimental results on the compressibility of strongly coupled (nonideal) degenerate deuterium and helium plasmas quasi-isentropically compressed to pressures
P
~ 20 TPa in devices ...with a spherical geometry. The trajectories of the plasma-compressing metallic shells were recorded with the help of powerful pulsed X-ray sources (betatrons) with a boundary electron energy of 60 MeV. A high-current accelerator with a penetrability of objects with an equivalent thickness of 250-mm of lead has been used for the first time as an X-ray source in our experiments. Plasma densities up to ρ ≈ 14 g cm
–3
were determined from the measured radius of the shell at the instant of its “stopping.” We derived the compressed-plasma pressure based on our gasdynamic computations including the real characteristics of the experimental devices.
Here, the synthesis of holey carbonylated (C-ny) graphene derivative and its application for gas sensing is demonstrated. The carbonylation of graphene oxide leads to the 3-fold increase in the ...concentration of carbonyl groups’ up to 9 at.% with a substantial elimination of other oxygen functionalities. Such a chemical modification is accompanied by the perforation of the graphene layer with the appearance of matrices of nanoscale holes, leading to corrugation of the layer and its sectioning into localized domains of the π-conjugated network. Combined with the predominant presence of carbonyls, granting the specificity in gas molecules adsorption, these features result in the enhanced gas sensing properties of C-ny graphene at room temperature with a selective response to NH3. Opposite chemiresistive response towards ammonia when compared to other analytes, such as ethanol, acetone, CO2, is demonstrated for the C-ny graphene layer both in humid and dry air background. Moreover, a selective discrimination of all of the studied analytes is further approached by employing a vector signal generated by C-ny multielectrode chip. Comparing the experimental results with the calculations performed in framework of density functional theory, we clarify the effect of partial charge transfer caused by water and ammonia adsorption on the chemiresistive response.
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•GO can be converted to the carbonylated graphene containing up to 9 at.% of carbonyls.•Carbonylation leads to holey and corrugated structure of graphene layer.•Holey-matrixed structure and carbonyls enhance graphene gas sensing properties.•Carbonylated graphene exhibits an exceptional selectivity regarding the NH3 detection.
X-Ray Fluorescence analysis based on excitation with 109Cd source and registration of characteristic X-rays with Si(Li) detector was used to record the kinetics of desorption of Kr and Xe from ...carbonaceous samples of 1–100 mg after their treatment with the inert gases at temperatures from 20 to 700 °C. Activated coals with a known pore distribution were used to demonstrate that the Kr desorption half-life is inversely proportional to the square of the pore diameter in the range from 0.7 nm to 50 nm. Although the absorption of Xe was 2–10 times higher in the same pores than the absorption of Kr, the desorption of Xe was about 2.83 times slower than the desorption of Kr. The later fact speaks in favor of using Kr and Ar as a marker for evaluating porous structures rather than Xe.
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•Simultaneous ED-XRF control of Kr, Xe, Fe, Cu, Zn, Pb, and H in carbon samples.•Evaluation of pore diameters by halftimes of Kr and Xe desorption.•Clarification of correlations between metallic admixtures and pore distribution.•In the same pores, Xe desorption is by 2.83 times slower than that of Kr.
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The study of the elemental composition of labile humus substances passing into 0.1 M NaOH extract from typical chernozem under different cenoses indicated that, judging from the H : C ratio varying ...within 1.55–1.91, aliphatic structures predominate over cyclic components. Under the agrogenic impact, the processes demethylation, dehydrogenation, and oxidation of organic substances are developed in the chernozem. As a result, labile humic substances lose their aliphatic components and become enriched with oxidized nitrogen-containing cyclic structures. The intensity of this process increases in the series: permanent winter wheat > permanent corn > permanent bare fallow. At the same time, labile humic substances of the chernozem under permanent bare fallow are the least energy-intensive compounds as judged from the values of the heat of combustion found on the basis of elemental analysis data. Over the 23 years that have passed since the transfer of the permanent bare fallow to the unmanaged fallow overgrown by herbs, there have been no significant changes in the elemental composition of labile humus substances of typical chernozem, except for a tendency of their enrichment in newly formed aliphatic nitrogen-containing reduced and more energy-intensive compounds.
When a charged membrane separates two salt solutions of different concentrations, a potential difference appears due to interfacial Donnan equilibrium and the diffusion junction. Here, we report a ...new mechanism for the generation of a membrane potential in polarizable conductive membranes via an induced surface charge. It results from an electric field generated by the diffusion of ions with different mobilities. For uncharged membranes, this effect strongly enhances the diffusion potential and makes it highly sensitive to the ion mobilities ratio, electrolyte concentration, and pore size. Theoretical predictions on the basis of the space-charge model extended to polarizable nanopores fully agree with experimental measurements in KCl and NaCl aqueous solutions.
The growth of single crystal diamond plates in a microwave plasma using H2-CH4 and H2-CH4-Ar gas mixtures in a broad range of methane concentration (2–15%) is studied. The growth rates up to 60μm/h ...in H2-CH4 mixtures and up to 105μm/h in Ar-H2-CH4 mixtures are achieved at high CH4 content, without adding nitrogen, still obtaining transparent crystals. The thermal conductivity k of the SCs in the temperature range of 220–420K is measured by a laser flash technique. High thermal conductivity k≈2300W/m⋅K at room temperature is found for the sample grown at low growth rate in H2-CH4, this value reducing to k≈2000W/mK for the material produced in high rate regime at 15% CH4. The spatial profiles of Hα and C2 line intensities in the plasma were determined with optical emission spectroscopy (OES). Soot formation at high CH4 contents is observed at the plasma border both for Ar-free and Ar-containing mixtures, the soot yield being roughly proportional to diamond growth rate. The soot temperature Ts, as measured with OES, is almost constant (3800±300K) in H2-CH4 mixtures over the all methane concentration range explored, while for Ar-containing plasma the Ts is even higher (4100–4200K) at CH4<10%, reducing, however, below 3800K in CH4-reach mixtures. Raman spectra of collected soot correspond to crystalline graphite with high density of defects. The estimated carbon conversion efficiency from CH4 precursor to the soot can exceed 10% and should be taken into account in overall carbon balance in the CVD process.
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•Single crystal (SC) diamond films are grown in a microwave plasma using H2-CH4 and H2-CH4-Ar gas mixtures in a broad range of methane concentration (2–15%) at the growth rates up to 105μm/h without nitrogen addition. Optical absorption, Raman and photoluminescence spectroscopy confirm the high quality of the produced material.•Spatial distribution of gas temperature Ts in the plasma as well as of Hα and C2 line intensities are determined with optical emission spectroscopy (OES), the temperature Ts profiling being obtained from the shape of continuous component of the OE spectra.•The thermal conductivity as high as k≈2300W/mK at room temperature is measured by a laser flash technique for low growth rate samples and ≈ 2000W/mK for high growth rate (≈60μm/h) material.•The soot is formed at high methane contents and/or Ar gas addition in the reaction mixture with the rate roughly proportional to CH4 percentage. The mass yield for the soot can be an order of magnitude higher than that for diamond.
The quasi-isentropic compressibility of a strongly nonideal helium plasma in the pressure range 250–600 GPa is experimentally studied in devices with cylindrical geometry. The temperature at the ...front of a cylindrical shock wave in helium (
T
≈ 10 000 K) and the flight speed of the inner cascade (
W
≈ 3.5 km/s), in the cavity of which the maximum compressed plasma density is achieved, are measured. Data on the compression of a nonideal helium plasma to a density ρ ≈ 3 g/cm
3
at an approximately constant final temperature of 21000 K are obtained. The trajectories of the metallic shells compressing the plasma are detected using high-power pulsed X-ray sources with a boundary electron energy of up to 60 MeV. The helium plasma density is determined using the radii of the shells measured at the time of their “stop.” The compressed plasma pressure is obtained using gasdynamic calculations. Comparative theoretical calculations of the quasi-isentropic compression parameters have been carried out using the following two theoretical models: the traditional chemical plasma model (SAHA code) and an ab initio quantum molecular dynamics (QMD) approach. No anomaly of the experimental data in the pressure range of the plasma phase transition theoretically assumed in helium is detected.
Techniques for the absolute calibration of radar reflectivity Z and differential reflectivity ZDR measured with dual-polarization weather radars are examined herein. Calibration of Z is based on the ...idea of self-consistency among Z, ZDR, and the specific differential phase KDP in rain. Extensive spatial and temporal averaging is used to derive the average values of ZDR and KDP for each 1 dB step in Z. Such averaging substantially reduces the standard error of the KDP estimate so the technique can be used for a wide range of rain intensities, including light rain. In this paper, the performance of different consistency relations is analyzed and a new self-consistency methodology is suggested. The proposed scheme substantially reduces the impact of variability in the drop size distribution and raindrop shape on the quality of the Z calibration. The new calibration technique was tested on a large polarimetric dataset obtained during the Joint Polarization Experiment in Oklahoma and yielded an accuracy of Z calibration within 1 dB. Absolute calibration of ZDR is performed using solar measurements at orthogonal polarizations and polarimetric properties of natural targets like light rain and dry aggregated snow that are probed at high elevation angles. Because vertical sounding is prohibited for operational Weather Surveillance Radar-1988 Doppler (WSR-88D) radars because of mechanical constraints, the existing methodology for ZDR calibration is modified for nonzenith elevation angles. It is shown that the required 0.1-0.2-dB accuracy of the ZDR calibration is potentially achievable.
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