A paper presents the problem of results reliability increasing a during person's condition diagnosing by pulse oximeter is considered. A new method for reliability evaluation of the measurement ...results of the pulse wave parameters and a technique for tuning of optical part of the pulse oximeter are developed. Developed by us the method and the technique allow to make the insignificant of number errors influence on the measurement results. The data on the experimental research of various people condition are presented.
The article discusses the using of the rubidium - 87 quantum frequency standard for satellite navigation systems. A method for improving the parameters of the microwave excitation signal to enhance ...the short-term and long-term stability of the standard is proposed. The results of experimental studies are presented.
Abstract
One of the negative factors that affects the performance of various works on the Earth’s surface are voids in the surface part of the earth’s section. They are formed for various reasons. In ...most cases, these reasons are associated with irresponsible human activities. This can be excavation through adits, groundwater abstraction, or a breakthrough of underground utilities. In some cases, a disturbance in the ecological balance leads to the fact that the rivers go underground. Large areas of earth and sandstone are washed away. There is a danger of a collapse of the territory. Heavy rains are exacerbating this situation. These formed voids must be identified in a timely manner. Therefore, in places of their possible formation, it is necessary to constantly monitor the territory. The paper proposes an easy-to-use method for detecting these voids by imaging using refracted waves. For this, the collected data was processed using two different techniques. In the first case, the correlation of the first peaks on all seismograms is performed. This made it possible to obtain a depth-velocity section. The second method consists in reducing the travel time curves of the first refracted wave and obtaining a summarized seismic section. In this case, voids are distinguished by the loss of correlation of the axes of in-phase of the reduced time. This allows you to identify even small voids that form under the soil. With the deterioration of the ecological state, more and more voids are formed. To eliminate them, it is necessary to take prompt measures.
The article presents the methods for calculating the stability of the rubidium frequency standards. To implement these methods, new software has been developed. Experimental measurements of ...telemetric parameters of the quantum frequency standard are processed using the developed software. The stability of the prototype of the rubidium standard has been determined using the proposed new algorithms.
The relationship of the spectral luminescent and nonlinear optical properties of Ag2S quantum dots (QDs), passivated with thioglycolic acid (Ag2S QDs/TGA) and Ag2S QDs, stabilized by gelatin (Ag2S ...QDs/Gel) with average sizes from 1.5 nm to 2.1 nm is found. Colloidal Ag2S QDs/TGA with different sizes, having the exciton (620 nm) and recombination (660 nm, 880 nm and 1205 nm) luminescence were studied using the methods of luminescent spectroscopy, luminescence decay, and Z-scans technique at the wavelengths of 532 nm using 10 ns pulses. Resonant two-photon transitions of reverse saturated absorption (RSA) were found for samples with recombination luminescence. In addition, the nonlinear refraction of thermal nature was observed using Z-scan method. Predominantly weak two-photon absorption (TPA) and nonlinear refraction (NR) of non-thermal nature occur for Ag2S/TGA quantum dots with exciton luminescence. The luminescence lifetimes support this conclusion. The differences in luminescence lifetimes of samples are associated with different state of interfaces for colloidal Ag2S QDs/TGA with recombination and exciton luminescence. This conclusion was confirmed by FTIR spectroscopy of colloidal Ag2S QDs/TGA solutions, synthesized under different conditions. RSA is characteristic of samples with a noticeable concentration of trap states acting as recombination luminescence centers (660 nm). The maximum effect was noted for Ag2S QDs with recombination luminescence in the region of 660 nm, 880 nm, 1205 nm. The fast component of this luminescence decay has a time constant of about 0.8 ns. It decay 5 times for the first 10 ns. In the case of Ag2S QDs/TGA with exciton luminescence (620 nm) there are no appropriate conditions for RSA. The fast component of luminescence decay has a time constant of 0.8 ns. The luminescence intensity decreases 50 times for the first 10 ns. In this case, TPA and nonlinear refraction of non-thermal nature take place, and RSA is absent.
Abstract
The article discusses the main disadvantages of the current design of a quantum frequency standard based on rubidium-87 atoms. The main disadvantages of the current design of the quantum ...frequency standard on rubidium-87 atoms are considered. It is noted that the processes associated with light shifts in the optical part contribute to the greatest instability in the long-term operation of the quantum frequency standard. A solution is proposed to improve the design of the rubidium standard. A forecast for improving its metrological characteristics is presented. The results of experimental investigations are presented.
In the article a methods of results reliability increasing during diagnosing a person's condition by pulse oximeter are considered. A new method of estimating the reliability of the measurement ...results of the parameters of the pulse wave and the method of tuning the optical part of the pulse oximeter are proposed. The use of this technique allows to make the insignificant of number errors influence on the measurements results. The experimental data about the various people condition research are presented.
The study is devoted to the establishment of plexciton coupling manifestations in the luminescence of colloidal CdS quantum dots (3.7 nm), passivated with Oleic acid (OA) in mixtures with spherical ...silver nanoparticles (Ag NPs), coated with Oleylamine (OAm) with size of 10–15 nm. Mixtures of CdS QDs and Ag NPs in toluene, in which the associates formation occurs as a result of the π-staking and dipole-dipole interaction have been realized. The case of the simultaneous effect of plasmonic nanoparticles on exciton and trap state luminescence is considered. Under conditions of maximum overlap of Ag NPs extinction spectrum (415 nm) and exciton luminescence band, it was found that the exciton luminescence quenching (430 nm), accompanied by an decrease in its lifetime from 7.4 ns to 2.5 nm due to resonance energy transfer with an efficiency of 0.66 is dominant effect. At the same time, under conditions of weak plexciton coupling, caused by an insignificant overlap of Ag NPs plasmon band, an increase in the intensity of trap state luminescence (603 nm) by a factor of 1.8 with simultaneous decrease in its luminescence lifetime from 75 ns to 25 ns was observed due to the manifestation of the Purcell effect. The obtained results demonstrate the possibility of increasing the quantum yield of QDs trap state luminescence due to the Purcell effect.
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•The plexciton coupling manifestations in the luminescence of colloidal CdS quantum dots with spherical silver NPs is studied.•Exciton luminescence quenching is observed under conditions of maximum overlap of Ag NPs extinction spectrum and exciton luminescence.•Under conditions of weak plexciton coupling an increase in the trap state luminescence intensity was observed due to the Purcell effect.
At article of the main factors rendering of influence on the reliability of material control results by ultrasonic thickness gauge are determined. The necessity of the use of automatic calibration of ...ultrasonic thickness gauge for reduction of measurement error is justified. The neural network for the realization of automatic device calibration is developed. The received experimental results are presented.
Abstract
The problems that arise in the surface layer of the soil during periodic emissions at nuclear power plants are considered. The necessity of constant monitoring of this soil layer at ...different times of the year is substantiated. Various methods of this control are considered. It has been established that it is extremely difficult to implement them in remote areas. A method has been developed for monitoring the surface layer of the soil using aerodynamic survey of the distribution of γ-radiation on the soil surface. This is extremely important during the preparation of agricultural fields for sowing crops in the spring. A new algorithm for restoring images obtained using aerodynamic imaging of γ-radiation is proposed. The results of a new algorithm for image processing and identification are presented.
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