Application of Forced Modulation Function Mathematical Model in the Characteristic Research of Reflective Intensity Fibre Sensors

In order to discuss the application and mode of the forced modulation function in a sensor, the optical fibre emphasis function was established by referring to the geometric method, the tilt factor and the shape factor of the reflecting surface. These were introduced for the first time, and the corresponding mathematical model was established. The method of numerical simulation is systematically studied and multimode optical fibre parameters (including optical fibre of axial spacing, optical fibre core diameter and numerical aperture) are adopted. The reflective surface inclination and shape factors on the RIM–FOS intensity modulation characteristics are studied according to the obtained light quasi-Gaussian distribution model, establishing a general three-intensity modulation function of fibre optic sensor. The results show that the intensity modulation characteristic of specular reflection is obviously better than that of the diffuse reflection surface, and the peak value of the modulation function is five times that of diffuse reflection. The intensity modulation characteristic decreases with increase in the roughness of the reflection surface. The system can not only complete the RIM–FOS characteristic simulation and characteristic testing functions, but can also start-up the test and not be affected by the ambient light interference and power fluctuation of the light source. The test stability is good with high repeatability.

Demonstration of light reflection concepts for rendering realistic 3D tree images

With advancements in computer graphics, creating natural images has always been the main purpose, image rendering is all based on principles of physics. So, understanding the physics of image rendering will enable us to create the most realistic images. A ray of light hit a surface with different orientation and reflects as per the rules of physics. It is difficult to calculate the light reflection of complex foliage, such as trees, so, the reflection of this natural complexity needs to be adapted to rendering situations. In this research, the researchers provide demonstrations to enable students to understand the light reflection in nature, light calculation in computer graphics and methods to apply them to render realistic tree images. The researchers assign students to render 3D realistic tree images to assess the students’ understanding by applying the diffuse reflection value, specular reflection value and surface normal direction to render realistic tree images. The researchers find that most students understand of diffuse reflection, specular reflection, and surface normal direction causes the rendering results to be most realistic.

MIXED-LIGAND HETEROMETALLIC COMPLEXES OF Ge(IV)-M2+ (Mn, Fe, Co, Ni, Zn) WITH 1,3-DIAMINO-2-HYDROXYPROPANE N,N,N',N'-TETRAACETIC ACID

There have been developed a novel synthetic method that allowed to obtain raw of mixed-ligand heterometallic binuclear complexes of Ge(IV)-M2+ (Mn, Fe, Co, Ni, Zn) with 1,3-diamino‑2-hydroxypropane N, N, N’, N’-tetraacetic acid (H5hpdta). Compounds have been characterized by the set of methods: elemental analysis, thermogravimetry, IR‑spectroscopy, spectrum of diffuse reflection, magnetic suspensibility. According to the elemental analysis, the molar ratio Ge: M: H5hpdta: bipy= 1:1:1:1 in the obtained compounds 1‑5 corresponds to the formula [(H2O)(OH)Ge(m-hpdta)M(bipy)]·nН2О (M=Mn n=3 (1), Fe n=2 (2), Co n=4 (3), Ni n=4 (4), Zn n=3 (5). Complexes have yellow (1), red (2), orange (3), violet (4) and pink (5) colors and are stable on air. Compounds 1‑5 exist in the form of crystal hydrates, that contain certain amount of water molecules, that are eliminated into the gas phase while heating in the wide range of temperatures (t=80‑250 °C), which is accompanied with the low-temperature endothermic effect. This indicates the presence of a system of stable hydrogen bonds in their crystal structure. Analysis of the IR‑spectra 1‑5 revealed that form and coordination of ligands is similar. Deprotonation of all carboxylic groups in the ligands (H5hpdta) and their bonding to germanium and d-metal is confirmed with the absence in the IR‑spectra 1‑5 absorption bands characteristic for the free СООН H5hpdta (1716 сm‑1) and nas(СОО-) і ns(СОО-) bands. Disappearance of the ν(С-OН)-1210 сm‑1 and appearance of the ν(С-O)alk., νas(Ge-O-M), νs(Ge-O- M) absorption band indicates that OH‑group of H5hpdta is deprotonated and performs bridging function. 2,2`-bipyridine bidentatly coordinates to the d-metal, binds to the O, N‑atoms of hpdta5- ligand and reaches coordination number 6. The last ligand plays the bringing role between Ge-dmetal, shows itself as ditopic, octadentate in total. According to the magnetic moments of 3, 4 and their diffuse reflection spectra, polyhedrons of Co (II), Ni (II) are octahedrons, which are realized due to the bidentate coordination of bipyridine and four bonds with nitrogen and oxygen of hpdta5-. Structure of heterometallic binuclear complexes 1‑5 is similar. Ligand hpdta5- shows itself as octadentate ditopic, all carboxylate groups monodentatly coordinate to metals, oxygen atom of the deprotonated OH‑group performs the bridging function.

Rational Design and Synthesis of ZnWO4 Nanorods Decorated with SnS Nanodots with Enhanced Visible-Light Photocatalytic Performance

Aiming to construct a direct Z-scheme binary heterostructure for efficient degradation of the organic dye Rhodamine B (RhB), ZnWO4 nanorods decorated with SnS nanodots were rationally designed and prepared via a facile two-step route. Morphological observation and structural study showed that ultra-fine SnS nanodots were anchored on the surface of ZnWO4 nanorods to form an intimate contact between the two components. Such a special structure provided SnS/ZnWO4 nanocomposites with significantly enhanced light harvesting capacity, revealed by the results of UV-vis diffuse reflection spectroscopy (DRS). Photoluminescence (PL) analysis in combination with electrochemical measurements demonstrated that the recombination of photoactivated charge carriers was efficiently inhibited and the transfer of photoactivated charge carriers was successfully achieved due to the introduction of SnS. The degradation rate over SnS/ZnWO4 nanocomposites reached a maximum value at SnS content of 9 wt%. The significantly enhanced photoactivity of SnS/ZnWO4 nanocomposites was imputed to the synergistic effect of the promoted light absorption ability and effective photogenerated charge carriers’ transfer and separation.

Determination of the bottom scattering coefficient discontinuity lines in the multibeam ocean sounding

In this paper the problems of constructing sonar images of the seabed according to measurements of the multibeam side scan sonar are considered. The inverse problem for the non-stationary equation of radiation transfer with the diffuse reflection conditions at the boundary which consists in finding the discontinuity lines of the bottom scattering coefficient is investigated. A numerical algorithm for solving the inverse problem is developed, and an analysis of the quality of reconstructing the boundaries of inhomogeneities of the seabed is carried out, depending on the number of views and the width of a radiation pattern and the sounding range.

Model of diffuse reflection of optical radiation from the surface of biological tissue, implemented on the basis of two-dimensional fractional Brownian motion process

The numerical model of the diffuse reflection of Gaussian beam from the surface of biological tissue is introduced. The two-dimensional fractional Brownian motion (fBm) with the Hurst index H and the scale parameter σ was used for the simulations of the tissue surface relief. For the surfaces described by fixed σ = 0.1 and H = 0.55, H = 0.803 (corresponds to the surface of a banana fruit), H = 0.9, the angular distributions of the reflected radiation intensity were calculated using a Kirchhoff integral approach. The resulting distributions considerably differ from each other. Therefore, the introduced model can be used for the solution of the inverse problem of finding the fBm parameters of tissue surfaces employing the experimentally measured distribution of the reflected radiation intensity.

Construction of ZnO/Keggin Polyoxometalate Nano Heterojunction Catalyst For Efficient Removal of Rhodamine B in Aqueous Solution

In this paper, we synthesized two novel heterojunction nanocomposite catalysts ZnO/Ag4SiW12O40 and ZnO/Cs3PW12O40 by a simple dissolution-precipitation method. The structure and morphology of the samples were analyzed by XRD, TEM, FT-IR, Raman, UV diffuse reflection, XPS and N2 adsorption desorption isotherm. Compared with pure ZnO, the composite catalyst formed with Ag4SiW12O40(AgSiW) and Cs3PW12O40(CsPW) can significantly improve the problem of fast recombination rate of photogenerated carriers in ZnO, and broaden the response range of ZnO to visible light. Rhodamine B (RhB) was used as a simulated pollutant to investigate the photocatalytic degradation performance of the composite catalyst. The experimental results show that the photocatalytic degradation activity of the prepared composite catalyst is much higher than that of pure ZnO, and the degradation performance of ZnO/Ag4SiW12O40 is stronger. Finally, the possible photocatalytic mechanism of ZnO/Ag4SiW12O40 and ZnO/Cs3PW12O40 heterojunction nanocomposite catalysts was proposed by UV diffuse reflection, free radical capture experiment and Mott Schottky test.

A New Method of Measuring Retinal Vessel Diameters from Fundus Photographs Based on Retinal Structure and Light Reflection

<p>We propose a new method and software for measuring blood vessel diameters from fundus photographs. In this method the edge of the blood vessel is the two minimum points in the luminance profile and diameter is distance between minimum points. We noticed the relation between W-shape of luminance profile at blood vessel transversal line and cylindrical shape, and analyzed the validity of this method using the diffuse reflection model of a cylinder shape based on the optics. The simulation image by the diffuse reflection model of the cylinder was similar to that of the blood vessel images. A newly developed software using the minimum points can measure repeated measurement in a series of photographs at the same point of the same person. The data of the repeated measurement of each person showed stability, and the coefficient of variation showed no affection of different diameter and arteriovenous distinction. Hence, we believe that the minimum points are valid as blood vessel edges. The software that measures these blood vessel edges has an extremely simple measurement procedure, possesses few errors, and is easy to automate. This method is relevant because the central reflex, which has not been utilized previously, optically represents the cylindrical three-dimensional structure of blood vessels.</p><div><div> </div> </div>