Search

The possibility of using the thermal imaging method to assess the level of blood flow in the course of building thermograms of the surface of the hands of healthy volunteers before and after the load on the muscles was studied in this paper. The results obtained using the thermal imaging method provide objective information about the degree of blood supply to the tissues, which opens up new perspectives for evaluating skin blood flow in the dynamics. The technique is absolutely safe, non-invasive, versatile and easy to perform.

An automated low-background NaI(Tl) gamma-ray spectrometer for in situ underwater measurements consisting of a submersible unit with a radiation detector and of a surface microcomputer unit is developed and described. Along with an ultra low-background NaI(Tl) radiation sensor, the submersible unit contains a specially designed FPGA-based electronics with low energy consumption and with abilities both for remote data acquisition by a 1200 m conducting cable and for an autonomous operation mode. The unit is enclosed in a waterproof polyacetal housing withstanding a pressure of 4 MPa at a depth of 400 meters. The surface microcomputer unit contains an all-in-box software for acquisition, storage, and processing of data from the detector unit, for real-time monitoring of activities of dissolved radionuclides, for their identification and quantification. The software functions are accessed remotely by a web-interface using Wi-Fi or Ethernet. Several techniques for gain control (including an auto-adjustment of the gain by setting a selected photopeak in a prescribed channel) together with the corresponding approaches to the energy-scale calibration are implemented and examined over a wide temperature range − 10 ÷ + 50 ° C in a thermo-chamber calibration experiment with 152 Eu point gamma-ray sources . Calibrating the energy resolution of the detector is performed from line-width measurements of reference gamma-ray sources. The detection-efficiency calibration is carried out using Monte Carlo simulations based on the GEANT4 code taking into account the materials and geometry of the detector as well as the water environment. In addition, the efficiency of the detector immersed in a 8 m 3 water tank with dissolved gamma-ray sources of 139Ce, 137Cs and 40K of known activities is determined experimentally and compared with the theoretical findings. Finally, a trial deployment of the gamma-spectrometer in the Yellow Sea together with test measurements of the activity concentrations of dissolved radionuclides is fulfilled. The Minimum Detectable Activity concentrations (MDA) for 137Cs in fresh and sea water are calculated from the water tank experiment and from the test deployment experiment correspondingly.

The Varshni parameters of the temperature dependence of the bandgap energy in the range 10–313 K and the temperature dependence of the spin–orbit splitting energy have been calculated using experimental data obtained for an InAs0.88Sb0.12 active layer. Amplified luminescence was observed in the range 10–35 K for LEDs based on InAs0.88Sb0.12/InAsSbP heterostructures. The sharp drop in radiation intensity of InAsSb/InAsSbP LEDs at temperatures >32 K was due to extensive growth of the CHCC Auger-recombination process while the CHSH process was the dominant Auger-recombination process at temperatures

The feasibility of using light-emitting devices, the radiation spectrum of which has maxima at wavelengths of 1.7, 1.9, and 2.2 μm for determining the water concentration in oil and oil products (gasoline, kerosene, diesel fuel) has been demonstrated. It has been found that the measurement error can be lowered if (i) the temperature of the light-emitting diode is maintained accurate to 0.5–1.0°C, (ii) by using a cell through which a permanently stirred analyte is pumped, and (iii) by selecting the repetition rate of radiation pulses from the light-emitting diodes according to the averaging time. A meter of water content in oil and oil products has been developed that is built around IR light-emitting device–photodiode optrons. This device provides water content on-line monitoring accurate to 1.5%.

The spectral characteristics of light emitting diodes based on a InAs/InAsSb/InAsSbP heterostructure, which emit in a wavelength range of 3.5–4.5 µm, are investigated experimentally. It is shown that the temperature shift of the maximum emission wavelength of a light emitting diode in the temperature range 80–313 K is 1.8 nm/K. The temperature dependence of the band gap of the InAs0.88Sb0.12 active layer is described by the Varshni formula with the characteristic parameters: Eg0 = 0.326 eV, a = 2.917 × 10–4 eV/K, and s = 168.83 K. The results of our measurements of the concentrations of carbon dioxide (CO2) using the studied light emitting diodes show the possibility of the reliable detection of CO2 in the concentration range 300–100000 ppm.

It has been theoretically ascertained that for defect-free InGaAs and InGaN compounds the uniform distribution of indium atoms is more energetically preferable than the clustering distribution. The presence of gallium and arsenic vacancy in InGaAs and nitrogen vacancy in InGaN facilitates indium atom clustering distribution. It has been shown that the increase in the indium content in InGaAs and InGaN compounds leads to the decrease of the formation energy of gallium, arsenic and nitrogen vacancies.

This article is deal with the experimental investigations of the laser diode matrixes (LDM) based on the AlGaAs/GaAs heterostructures (lasing wavelength 790-880 nm) to find optimal LDM parameters for active vision systems. In particular, the dependence of LDM radiation pulse power on the pulse duration and LDA active layer heating as well as the LDM radiation divergence are discussed.