Conversion of the wavelength distribution to the energy spectrum of the wave

When designing a vessel, spectral calculating methods of wave induced oscillation are used, and during vessel operation, available technical means allow us to obtain only the pitch spectrum. For a complete solution of navigational tasks, it is necessary to have a wave disturbance spectrum and pitch amplitude-frequency characteristic as well. The latter function can be received in sailing, if obtaining the actual wave disturbance spectrum is possible. The lack of available and sufficiently accurate methods of actual wave disturbance assessment in modern navigation creates the need to use statistical mathematical models in addition to available information in order to connect various wave elements. Taking into account the possibility of obtaining the wavelength distribution from the wave field radar image, a hypothesis is formulated about the possibility of using a statistical mathematical connection between the wind wave lengths and heights. Within the proposed hypothesis, an algorithm is presented for converting the actual wavelength probability distribution obtained from wave field radar images into the disturbance frequency spectrum. The conclusion is made about possible application of the hypothesis in pitch transfer function assessment.

Applications of Different Light Spectra in Growing Forest Tree Seedlings

Light intensity, duration and wavelength distribution are amongst the most important factors affecting the success of plant production in different cultivation systems [...]

Exact resolution function for double-disk chopper neutron time-of-flight spectrometers: application to reflectivity

The exact resolution function of the transfer vector for the HERMÈS reflectometer at the Laboratoire Léon Brillouin is calculated as an example of a neutron time-of-flight spectrometer with a double-disk chopper. The calculation accounts for the wavelength distribution of the incident beam, the tilt of the chopper axis, collimation and gravity, without an assumption of Gaussian distributions or the independence of these different contributions. A numerical implementation is provided. It is shown that data fitting using this exact resolution function allows much better results to be reached than with the usual approximation by a Gaussian profile.

Modeling dust emission in PN IC 418

We investigated the infrared (IR) dust emission from PN IC 418, using a detailed model controlled by a previous determination of the stellar properties and the characteristics of the photoionized nebula, keeping as free parameters the dust types, amounts, and distributions relative to the distance of the central star. The model includes the ionized region and the neutral region beyond the recombination front (photodissociation region, or PDR), where the [O I] and [C II] IR lines are formed. We succeeded in reproducing the observed infrared emission from 2 to 200 μm. The global energy budget is fitted by summing up contributions from big grains of amorphous carbon located in the neutral region and small graphite grains located in the ionized region (closer to the central star). Two emission features seen at 11.5 and 30 μm are also reproduced by assuming them to be due to silicon carbide (SiC) and magnesium and iron sulfides (MgxFe1−xS), respectively. For this, we needed to consider ellipsoidal shapes for the grains to reproduce the wavelength distribution of the features. Some elements are depleted in the gaseous phase: Mg, Si, and S have sub-solar abundances (−0.5 dex below solar by mass), while the abundance of C + N + O + Ne by mass is close to solar. Adding the abundances of the elements present in the dusty and gaseous forms leads to values closer to but not higher than solar, confirming that the identification of the feature carriers is plausible. Iron is strongly depleted (3 dex below solar) and the small amount present in dust in our model is far from being enough to recover the solar value. A remaining feature is found as a residue of the fitting process, between 12 and 25 μm, for which we do not have identification.

Accurate data processing for neutron Laue diffractometers

The factors affecting the accuracy of structural refinements from image-plate neutron Laue diffractometers are analysed. From this analysis, an improved data-processing method is developed which optimizes the intensity corrections for exposure scaling, wavelength distribution, absorption and extinction corrections, and the wavelength/spatial/time dependence of the image-plate detector efficiencies. Of equal importance is an analysis of the sources of uncertainty in the final corrected intensities, without which bias of the merged intensities occurs, due to the dominance of measurements with small statistical errors though potentially large systematic errors. A new aspect of the impact of detector crosstalk on the counting statistics of area detectors is reported and shown to be significant for the case of neutron Laue diffraction. These methods have been implemented in software which processes data from the KOALA instrument at ANSTO and the now decommissioned VIVALDI instrument at ILL (Grenoble, France). A comparison with earlier data-analysis methods shows a significant improvement in accuracy of the refined structures.

Модификация спектров фотопроводимости в композитных структурах ZnO-квантовые точки CdSe под действием дополнительного фотовозбуждения

The incorporation of CdS nanocrystals into a porous ZnO matrix results in sensitization of the composite in the visible spectral region. Studies of the photoconductivity spectra upon variable external illumination show that the spectra undergo reversible transformations. It is shown that the shape of the peak and the position of the local photoconductivity maximum corresponding to nanocrystals depend on the wavelength distribution of the incident radiation intensity. The mechanisms responsible for the process are discussed.

A comprehensive observational filter for satellite infrared limb sounding of gravity waves

This paper describes a comprehensive observational filter for satellite infrared limb sounding of gravity waves. The filter considers instrument visibility and observation geometry with a high level of accuracy. It contains four main processes: visibility filter, projection of the wavelength on the tangent-point track, aliasing effect, and calculation of the observed vertical wavelength. The observation geometries of the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) and HIRDLS (High Resolution Dynamics Limb Sounder) are mimicked. Gravity waves (GWs) simulated by coupling a convective GW source (CGWS) scheme and the gravity wave regional or global ray tracer (GROGRAT) are used as an example for applying the observational filter. Simulated spectra in terms of horizontal and vertical wave numbers (wavelengths) of gravity wave momentum flux (GWMF) are analyzed under the influence of the filter. We find that the most important processes, which have significant influence on the spectrum are the visibility filter (for both SABER and HIRDLS observation geometries) and aliasing for SABER and projection on tangent-point track for HIRDLS. The vertical wavelength distribution is mainly affected by the retrieval as part of the "visibility filter" process. In addition, the short-horizontal-scale spectrum may be projected for some cases into a longer horizontal wavelength interval which originally was not populated. The filter largely reduces GWMF values of very short horizontal wavelength waves. The implications for interpreting observed data are discussed.

A comprehensive observational filter for satellite infrared limb sounding of gravity waves

This paper describes a comprehensive observational filter for satellite infrared limb sounding of gravity waves. The filter considers instrument visibility and observation geometry with a high level of accuracy. It contains four main processes: visibility filter, projection of the wavelength on the tangent-point track, aliasing effect, and calculation of the observed vertical wavelength. The observation geometries of the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) and HIRDLS (High Resolution Dynamics Limb Sounder) are mimicked. Gravity waves (GWs) simulated by coupling a convective GW source (CGWS) scheme and the gravity wave regional or global ray tracer (GROGRAT) are used as an example for applying the observational filter. Simulated spectra in terms of horizontal and vertical wave numbers (wavelengths) of gravity wave momentum flux (GWMF) are analyzed under the influence of the filter. We find that the most important processes, which have significant influence on the spectrum are: visibility filter (for both SABER and HIRDLS observation geometries), aliasing for SABER and projection on tangent-point track for HIRDLS. The vertical wavelength distribution is mainly affected by the retrieval as part of the "visibility filter" process. In addition, the short-horizontal-scale spectrum may be projected for some cases into a longer horizontal wavelength interval which originally was not populated. The filter largely reduces GWMF values of very short horizontal wavelength waves. The implications for interpreting observed data are discussed.