Accuracy verification of low-cost CO2 concentration measuring devices for general use as a countermeasure against COVID-19

Within the context of the COVID-19 pandemic, CO2 sensors that measure ventilation conditions and thereby reduce the risk of airborne infection, are gaining increasing attention. We investigated and verified the accuracy of 12 relatively low-cost sensor models that retail for less than $45 and are advertised as infection control measures on a major e-commerce site. Our results indicate that 25% of the tested sensors can be used to identify trends in CO2 concentration, if correctly calibrated. However, 67% of sensors did not respond to the presence of CO2, which suggests that a type of pseudo-technique is used to display the CO2 concentration. We recommend that these sensors are not suitable for infection prevention purposes. Furthermore, 58% of the investigated sensors showed significant responses to the presence of alcohol. Owing to the widespread use of alcohol in preventing the spread of infectious diseases, sensors that react to alcohol can display inaccurate values, resulting in inappropriate ventilation behavior. Therefore, we strongly recommended that these sensors not be used. Based on our results, we offer practical recommendations to the average consumer, who does not have special measuring equipment, on how to identify inaccurate CO2 sensors.

Analysis of the Operating Modes of the Stationary Energy Storage Device in DC Railway Power Supply System

This article analyzes the operating modes of the energy storage. The aim was to conduct laboratory tests in conditions similar to real energy storage and to analyze its basic electrical parameters. A special measuring system has been created for laboratory testing. Real tests took place in the traction substation in Mińsk Mazowiecki, where the energy storage was included in the traction substation system. Based on the laboratory tests carried out and in real conditions it was found that the use of energy storage in the electric traction supply system is justified. It is adapted to work as a device supporting the operation of the traction substation and the section cabin.

Analysis of the affect of fluid container sizes on readings of Brookfield viscometer

Brookfield viscometers provide measurements viscosity directly in vessels with controlled liquids without transfer into a special measuring vessel. However, information on the degree and nature of the influence of these vessels dimensions on the measurement results is not presented in the literature. To increase the accuracy of viscosity measurements in vessels of arbitrary shape and size we conducted the experimental and theoretical studies of the LVF Brookfield viscometer sensitivity to the influencing quantities: the diameter of the vessel with a liquid, the distance from a spindle to the bottom of the vessel, and the level of immersion of the spindle. According to the technical documentation for Brookfield viscometers, viscosity measurements must be carried out in a Griffin beaker with a diameter of 83 mm and a volume of 600 ml or in a large vessel. The aim of this work is to determine the correction factors necessary for measuring viscosity in vessels whose sizes differ from those recommended. The general characteristic of factors influencing the accuracy of viscosity measurements is given. To determine the dependence of the viscometer readings on the vessel diameter a set of glass vessels with different diameters was used. To determine the dependence of the readings on the distance to the bottom of the vessel the liquid level in it was changed. When performing experiments, the temperature of the liquids was kept constant with an error of not more than 0,1 °C. Based on the known equations for rotational viscometers, expressions for approximating the dependences of the viscometer readings on the diameter of the vessel and the distance between its bottom and the end of the spindle are obtained. Formulas allowing to make corrections to the measurement results during the changing the mentioned influencing quantities are obtained. It was found that the distance from the spindle to the bottom of the vessel with the liquid affects the measurement results only when using the LV1 spindle and the immersion level affects only when using the LV4 spindle. The results of the viscometer calibration using the viscosity standards REV-100, REV-300, REV-1000, Brookfield 12500, Brookfield 100000 are presented. A correction factor of 1,04 for the case of using the LV3 spindle without a guardleg was obtained. The research results presented in the article allow applying a Brookfield viscometer for viscosity measurements in vessels with diameters up to 40, 30, 23, 10 mm for spindles LV1, LV2, LV3, LV4, respectively.

HoloPort – design and integration of a digital holographic 3-D sensor in machine tools

Manufacturing of high-precision components requires accuracies that even the most modern processing machines are often unable to deliver reliably. Slightly worn tools, incorrectly calibrated sensors or even different trajectories can lead to results that do not comply with the desired specifications. However, quality control is still mainly performed on randomized samples outside the machine tool in special measuring rooms. Therefore, closed-loop quality control becomes a cumbersome iterative process. With HoloPort, we present a digital holographic sensor system that is capable of measuring the complete topography of machined components with sub-micrometer precision directly inside a tooling machine. To our knowledge, HoloPort is the first wireless interferometric sensor inside a machine tool worldwide. As it is fully integrated, it features not only a multiwavelength interferometer but also a miniaturized graphics processing unit (GPU). This allows for full data evaluation directly in the sensor. A single measurement is taken and processed within 3 s during wireless operation. HoloPort is easy to integrate into a variety of machine tools. This contribution includes detailed information about the sensor architecture. Experimental results on milled parts demonstrate the performance of the system and illustrate possible inline applications as well as future perspectives for the sensor.

Method of Protecting Small Objects by Rockets on Near the Frontiers in Air and Space Defence System that Uses Special Measuring Range on the Basis of the Analysis the Frequency Deviation of the Received Signals

The article deals with the method of protection of small objects in the interests of air and space defence system through the use of spaced information subsystem using a special frequency range meter based on the analysis of the frequency deviation of the received signals reflected from guided missiles at near borders

Characterization of Atrial Septal Defect Occluders by right and left atrial pull-out forces

Occluders made of the shape memory alloy Nitinol are commonly used to close Atrial Septal Defects (ASD). Until now, standard parameters are missing defining the mechanical properties of these implants. In this study, we developed a special measuring setup for the determination of the mechanical properties of customly available occluders (i.e. Occlutech Figulla® Flex II 29ASD12 and AGA AMPLATZER™ 9-ASD-012).

Performance Degradations of MISFET-Based Hydrogen Sensors with a Pd-Ta2O5-SiO2-Si Structure During Long-Term Operation

We present the generalized experimental results of performance degradation of hydrogen sensors based on metal-insulator-semiconductor field effect transistor (MISFET)with the structure Pd-Ta2O5-SiO2-Si. The n-channel MISFET elements were fabricated on silicon single chips together with temperature sensors and heater-resistors by means of conventional -technology. Two hundred cycles of responses to different hydrogen concentrations were measured during eight weeks using special measuring and temperature stabilization circuitries with a feedback loop based on the chip’s thermo-sensor and heater. We show how the response parameters change during long-term tests of sensors under repeated hydrogen impacts. There were two stages of time-dependent response instability, the degradation of which depends on operating conditions, hydrogen concentrations, and time. To interpret results, we proposed the models, parameters of which were calculated using experimental data. These models can be used to predict performances of MISFET-based gas analysis devices for long-term operation.

Mathematical modelling and analysis of thermometric diagnostics of electrical products

The actual problem is the diagnosis and monitoring of the technical condition of the machines in operation, as well as the forecasting of their technical condition. The complexity of the problem of condition controlling is that the most informative characteristics of the electrical products can not be accurately determined without the use of special measuring transducers, which considerably increases the test time and makes it difficult to carry out continuous monitoring. A promising direction in solving this problem is the use of sensorless methods. Implementing these methods is based on using as a source of information the working winding of the electrical product, the active component of the resistance of which is determined just before the measurement of the magnetic characteristic and then used as a constant value. In the process of testing, there is heating and, as a consequence, a change in the active component of the winding resistance, which causes an unacceptable errors in determining the electrical products state. In this article the mathematical model of thermal processes are developed and analysis of thermometric diagnostics of electrical products is carried out.

The Impact of the Low Throw Fault on the Stability of Roadways in a Hard Coal Mine

Ensuring roadways stability in hard coal mines is one of the main challenges faced by engineers. A changeable geological structure have caused the roadway’s conditions to vary, thus influencing its stability. One of the causes of those changes is the presence of a previously undiscovered fault zone (small faults crossed the roadway) within which a significant convergence or support deformation may occur. The paper presents the impact of low throw faults on the degree of convergence of roadways. Convergence is determined for two roadways in the hard coal mine. A special measuring stations have been installed in one of the roadways, and they have carried out constant measurements for 15 months. In the other roadway, the degree of convergence has been determined on the basis of an on-site verification and comparison of the measurements obtained and the initial values, based on the roadway’s records. On the basis of the obtained convergence results, the impact of a single fault and the entire fault zone on the roadway stability has been determined. The impact of a single, low throw fault results in a 30% higher vertical convergence than in the case of roadways free of geological disturbance. In the roadway section located in the fault zone, vertical convergence is 4 times higher than in the case of sections free of disturbance impact. The floor heaving constitutes ca. 90% of vertical convergence both for roadway sections situated within the faulted zones and for sections free of the influence of any additional factors.