Rapid X-ray fluorescence analysis of intercalation compounds for molybdenum and cobalt content

Synthesizing and studying the properties of nanomaterials based on layered molybdenum disulfide, often face a need for rapid elemental analysis and prompt return of the material to the customer. Sometimes, nanoparticles of molybdenum disulfide are to be modified with metal compounds to improve the catalytic or magnetic properties of the material. We propose a method for rapid X-ray fluorescence determination of molybdenum and cobalt in the range of 10 – 50% in such compounds using a bulk method without dilution. Analytical signals were measured at the wavelengths of MoKα and CoKα lines using a VRA-30 spectrometer (Carl Zeiss, Germany; X-ray tube with Rh anode). The metal content was calculated using the derived coupling equations. The determination error ranges within ±2.7% (abs.) and 1.4% (abs.) for Mo and Co, respectively. Correctness of the method was confirmed for a batch of synthesized compounds by comparison of the results obtained with the data of XRF analysis using the dilution method traditionally used in the laboratory. The proposed rapid method provides simplification of the procedure and more than 4-fold shortening of analysis in time, the sample being preserved and can be used for further research.

Construction Features of The High-Precision Laser Rangefinder Light Modulator

The issues related to the development of a light modulator operating on the electro-optical effect of laser rangefinders by the modulation method are considered. To reduce the modulation power, it is proposed to lower the modulation frequency to 750-800 MHz, while simultaneously increasing the modulation quality to Q = 1000. The study of the phase determination error of a high-precision laser rangefinder depending on temperature showed that it is rational to construct the light modulator by radial installation of the KDP electro-optical crystal, with separated modulation and demodulation channels, while on combined resonators.

Структура, оптические и фотоэлектрические свойства пленок сульфида свинца, легированных стронцием и барием

The morphological evolution of composition, structural characteristics (lattice constant, microdeformations, texturing), optical and photoelectric properties of PbS films obtained by chemical bath deposition in the presence of ammonium iodide and strontium/barium chlorides at a concentration range up to 5 mmol/l was studied. According to elemental EDX analysis, the strontium content in PbS films was 0.4−0.7 at%, whereas barium concentration was beyond the determination error interval. The size of the particles forming the PbS films ranged from ~ 200 to ~ 400 nm with monomodal particle size distribution. The introduction of NH4I and SrCl2/BaCl2 into the bath retained the cubic B1 structure of PbS films, but led to a nonmonotonic change in the lattice parameter, which was associated with the defects, namely, vacancies or interstitial ions. The introduction of strontium and barium salts had no effect on the PbS band gap, but led to a change in the intensities of the impurity absorption bands in the depth and near the bottom of the conduction band. The dependence of the volt−watt sensitivity of the PbS films upon the concentration of strontium/barium in the solution was extreme with maxima at 0.05 and 0.1 mmol/l, respectively.

Determination of VVER-1000 Thermal Power Based on Background Signals of Self-Powered Neutron Detectors

The value of the reactor thermal power (RTP) is used in the VVER-1000 control systems in most algorithms for generation of control, blocking and protection signals. Besides, the technical and economic indicators of the power unit are determined by this parameter. Plans to increase VVER‑1000 RTP to 101.5%, and later to 104-107% of the nominal require additional justification of the accuracy of the RTP determination. Therefore, the task of increasing the accuracy of RTP determination is important. The paper describes the ways to improve the accuracy of weighted mean thermal power (WMTP) determination by selecting the optimal weight coefficient (that subsequently is used for WMTP determination) of each of the methods of RTP determination, namely: by thermotechnical parameters of the primary and secondary sides by neutron flux in the in-core monitoring system (ICMS) and in the neutron flux control equipment (NFCE). Another possibility of increasing the accuracy of WMTP determination, namely by increasing the number of methods of RTP determination, is also considered in the paper. The analysis of changes in the background signals of self-powered neutron detectors (SPNDs) during the VVER-1000 fuel campaigns shows the fundamental possibility of using the total background signal as a separate and independent method for RTP determination. The paper presents the results of the calculation of RTP determination error taking into account the coefficients of the components of the total RTP determination error: systematic, dynamic and random errors, which must be determined during the commissioning phase. The results of reduction of the error of WMTP determination in case of application of the additional method of RTP determination based on background signals of the SPNDs are presented. Theoretically, possible minimum values of the WMTP determination error are given depending on the values of the error of the RTP determination by separate methods.

Development and Implementation of the Robot Prototype with Inertial Navigation for Work in the Arctic

Currently, there is a very rapid development of robotics. People use robots in many areas of their activities. Especially valuable is the use of robots in hazardous conditions for humans, in particular in studies in the Arctic. In this case, there is an acute problem of navigation. The use of global navigation satellite systems (GNSS) in the Arctic is difficult due to the small number of satellites and the influence of Aurora. Therefore, we chose the inertial type of navigation for the prototype of the robot. We used LSM330DL micromechanical sensors and Atmega8-16AU microcontroller to create a navigation system. We used wireless access point Ubiquiti Bullet M2HP Titanium to connect the robot with researchers. Tests of a prototype of a robot on a wheeled platform showed that the coordinate determination error does not exceed 6%. Tests of the navigation system were carried out up to -20°C. System components allow operation up to -40°C. The proposed navigation system can be used to create robots for work in the Arctic.