In the above article <xref ref-type="bibr" rid="ref1">1 , a difference in the definitions of our simulated reflectance (with respect to instantaneous TOA radiance) and the operational MERSI-II L1 ...reflectance (with respect to solar constant) causes errors in their direct comparisons.
GenX is a versatile program using the differential evolution algorithm for fitting X‐ray and neutron reflectivity data. It utilizes the Parratt recursion formula for simulating specular reflectivity. ...The program is easily extensible, allowing users to incorporate their own models into the program. This can be useful for fitting data from other scattering experiments, or for any other minimization problem which has a large number of input parameters and/or contains many local minima, where the differential evolution algorithm is suitable. In addition, GenX manages to fit an arbitrary number of data sets simultaneously. The program is released under the GNU General Public License.
The use of X‐ray and neutron reflectivity has been generalized worldwide for scientists who want to determine specific physical properties (such as electron‐density profile, scattering‐length ...density, roughness and thickness) of films less than 200 nm thick deposited on a substrate. This paper describes a freeware program named REFLEX, which is a standalone program dedicated to the simulation and analysis of X‐ray and neutron reflectivity from multilayers. This program was first written two decades ago and has been constantly improved since, but never published until now. The latest version of REFLEX covers generalized types of calculation of reflectivity curves including both neutron and X‐ray reflectivity. In the case of X‐rays, the program can deal with both s and p polarization, which is quite important in the soft X‐ray region where the two polarizations can yield different results. Neutron reflectivity is calculated within the framework of non‐spin‐polarized neutrons. REFLEX has also been designed to include any type of fluid (such as supercritical CO2) on top of the analysed film and includes corrections of the footprint effect for analysis on an absolute scale.
REFLEX is a user‐friendly program dedicated to the analysis of specular X‐ray (soft and hard) and neutron reflectivity measurements.
In the San Francisco Bay Area, precipitation occurs in the wintertime, mostly as rain. Wintertime rainfall can be further classified into cold or stratiform rain with a typical radar bright band (BB) ...signature and warm orographic rain with the absence of a radar BB. Vertical pointing S-band profiler radar and disdrometer measurements from two of National Oceanic and Atmospheric Administration (NOAA)'s hydrometeorology testbed (HMT) sites in California are used to study the differences in microphysical properties between these two types of rain and their implications in radar rainfall estimation. A methodology has been developed to discriminate nonbright band (NBB) rainfall from BB rainfall using reflectivity (Z) and differential reflectivity (<inline-formula> <tex-math notation="LaTeX">Z_{\mathrm { DR}} </tex-math></inline-formula>) computed from disdrometer data. Delineating the two rainfall types in this way allowed for an algorithm to be applied to the radar scans to identify rainfall types and apply appropriate reflectivity-based and specific differential phase (<inline-formula> <tex-math notation="LaTeX">K_{\mathrm { DP}} </tex-math></inline-formula>)-based rainfall estimators. Recently, a gap-filling X-band weather radar with dual-polarization capabilities was deployed in the San Francisco Bay Area in Santa Rosa to aid in weather monitoring and provide high-resolution quantitative precipitation estimation (QPE) products. When applied to real radar observations, this method shows great potential for improving the QPE compared to traditional operational products which more often tend to underestimate rainfall in the California coastal region.
We compute electronic density of states, thermodynamic and optical conductivities of β-graphyne layer under applying biaxial strains. Particularly, the imaginary part of dielectric constant, which is ...proportional to the electromagnetic wave absorption rate, of β-graphyne due to the magnetic field and biaxial strain effects has been calculated. The temperature dependence of Pauli spin susceptibility and specific heat of the structure under applying magnetic field has been found. Tight binding model Hamiltonian has been applied for describing electron dynamics in β-graphyne layer in the presence of magnetic field. The effects of biaxial in-plane strain on the frequency behavior of the imaginary part of optical dielectric constant of β-graphyne layer. Linear response theory and Green’s function approach have been exploited to obtain the frequency behavior of optical behavior of the structure. Moreover, the frequency dependences of transmissivity and reflectivity of electromagnetic wave between two media separated by a β-graphyne layer are given. Our numerical results indicate that the frequency dependence of optical absorption shows a monotonic decreasing behavior for each compressive and tensile strain parameter. Also, the frequency dependence of transmissivity and reflectivity of electromagnetic wave between two media separated by β-graphyne layer for normal incidence has been investigated due to the effects of magnetic fields and strain parameters. The spin susceptibility of β-graphyne layer increases with magnetic field at fixed temperature however decreasing behavior for susceptibility is found for each value of magnetic field.
•The investigation of optical absorption of beta graphyne layer in the presence of Strain.•The study of transmission and reflection of electromagnetic wave between two media separated by graphyne layer.•The study of specific heat due to biaxial strain.
•We have determined the native oxide film thickness on several Al samples.•The results obtained from XRR and XPS show excellent agreement.•The results obtained from EIS show consistently thinner ...oxide films.•The oxides on the alloys are thicker than the oxides on the single crystals.
We present results from measurements of the native oxide film thickness on four different industrial aluminum alloys and three different aluminum single crystals. The thicknesses were determined using X-ray reflectivity, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In addition, atomic force microscopy was used for micro-structural studies of the oxide surfaces. The reflectivity measurements were performed in ultra-high vacuum, vacuum, ambient, nitrogen and liquid water conditions. The results obtained using X-ray reflectivity and X-ray photoelectron spectroscopy demonstrate good agreement. However, the oxide thicknesses determined from the electrochemical impedance spectroscopy show a larger discrepancy from the above two methods. In the present contribution the reasons for this discrepancy are discussed. We also address the effect of the substrate type and the presence of water on the resultant oxide thickness.
Many interesting physical, chemical and biological phenomena occur at interfaces between nanometre-scale layers of soft condensed matter. These often complex systems lend themselves to be studied by ...X-ray reflectivity (XRR) and neutron reflectivity (NR). The application of these techniques to such systems is extremely widespread and provides unique insights into their structure and dynamics. This review presents a snapshot of recent activity in this research area and identifies trends in the application of XRR and NR to novel, unusual or highly complex sample systems. Although the majority of research using these techniques is investigating variations on ‘traditional’ systems, supported by progress in instrumentation, advance sample environment and computational tools, NR and XRR have begun to produce singular insights into areas such as atmospheric science, real biological systems (cells and bacteria), oil–water interfaces or industrial problems (rheology, packaging or durability of nanomaterials).
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We propose a straightforward and efficient fusion-based method for enhancing weakly illumination images that uses several mature image processing techniques. First, we employ an illumination ...estimating algorithm based on morphological closing to decompose an observed image into a reflectance image and an illumination image. We then derive two inputs that represent luminance-improved and contrast-enhanced versions of the first decomposed illumination using the sigmoid function and adaptive histogram equalization. Designing two weights based on these inputs, we produce an adjusted illumination by fusing the derived inputs with the corresponding weights in a multi-scale fashion. Through a proper weighting and fusion strategy, we blend the advantages of different techniques to produce the adjusted illumination. The final enhanced image is obtained by compensating the adjusted illumination back to the reflectance. Through this synthesis, the enhanced image represents a trade-off among detail enhancement, local contrast improvement and preserving the natural feel of the image. In the proposed fusion-based framework, images under different weak illumination conditions such as backlighting, non-uniform illumination and nighttime can be enhanced.
•A fusion-based method for enhancing various weakly illuminated images is proposed.•The proposed method requires only one input to obtain the enhanced image.•Different mature image processing techniques can be blended in our framework.•Our method has an efficient computation time for practical applications.
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