Metrologické aspekty v analytické chemii: stanovení kovů ve vodách

The monitoring of water quality in the EU is described in detail and regulated by Directives of the European Commission and the Parliament, which underlines the importance of the quality of water (both potable and non-potable). Analysis of trace concentrations of contaminants in water, including metals, still presents challenges to demonstrate the quality and comparability of results. The article provides a detailed overview of the procedures that laboratories can use to assess the reliability of the results obtained by a particular measurement procedure. Emphasis is placed on three basic pillars: metrological traceability, validation and measurement uncertainty. Subsequently continuous evaluation is carried out using internal and external quality management measures. Regional aspects specific for the Czech Republic are also mentioned.

On the use of heated needle probes for measuring snow thermal conductivity

Heated needle probes provide the most convenient method to measure snow thermal conductivity. Recent studies have suggested that this method underestimates snow thermal conductivity; however the reasons for this discrepancy have not been elucidated. We show that it originates from the fact that, while the theory behind the method assumes that the measurements reach a logarithmic regime, this regime is not reached within the standard measurement procedure. Using the needle probe without this logarithmic regime leads to thermal conductivity underestimations of tens of percents. Moreover, we show that the poor thermal contact between the probe and the snow due to insertion damages results in a further underestimation. Thus, we encourage the use of fixed needle probes, set up before the snow season and buried under snowfalls, rather than hand-inserted probes. Finally, we propose a method to correct the measurements performed with such fixed needle probes buried in snow. This correction is based on a lookup table, derived specifically for the Hukseflux TP02 needle probe model, frequently used in snow studies. Comparison between corrected measurements and independent estimations of snow thermal conductivity obtained with numerical simulations shows an overall improvement of the needle probe values after application of the correction.

Estimation of the power of mechanical losses in the engine, transmission and wheels of car on the stand with running drums

The efficiency of a car is considered through the amount of energy loss spent on transmission from the engine to the driving wheels of the car. Analytical and experimental methods for assessing mechanical losses are analyzed. The advantages and disadvantages of road and bench tests of a car in free run modes are indicated. A description of the diagnostic equipment - a stand with running drums, used to simulate the movement of a car in laboratory conditions is given. The components of the necessary measuring equipment for recording the speed and torque on the wheels of a car are considered. The list of primary measuring sensors and main transducers is indicated, which transmit information to the computer. The results of the car run-out on the stand are given: the change in the instantaneous speed from time to time. The primary assessment of the regression model is made and the values of the coefficients are obtained by the method of least squares of deviations of the vehicle speed. A mathematical model for the subsequent processing of experimental data has been developed. The purpose of mathematical modeling is to separate mechanical losses by power units separately for the engine, transmission and car wheels. An assessment was made of the amount of energy losses in the stand itself with running drums. The characteristic of the stand has been obtained, which must be taken into account in the measurement procedure. The results of experimental studies for the GAZ-31029 car are presented. The results of the influence of the technical condition of transmission units and vehicle wheels on the value of the power of mechanical losses are presented. Car tire pressure studies have been conducted. The graphical dependences of the power of mechanical losses depending on the speed of the car are obtained. Recommendations have been developed for diagnosing the general condition of the vehicle by the amount of mechanical losses at the stand with running drums. The ways of further improvement of the method are given. The main conclusions based on the research results are formulated.

Validation of a measurement procedure for the assessment of the safety of buildings in urgent technical rescue operations

This work would like to provide a preliminary contribution to the draft of standard procedures for the adoption of Total Stations by rescuers in emergency situations, so as to offer a reliable and effective support to their assessment activities. In particular, some considerations will be made regarding the effect of the number and positioning of monitoring points on the tilt determination of a building façade, in order to set up simplified procedures, which are quick and easy to implement in emergency situations, at the same time guaranteeing the reliability of the results. Two types of building will be taken into account as test cases, which have different characteristics in terms of height, distance and angle with respect to the Total Station. Some considerations will be made about the aspects to be explored in future work, for the calibration of the method as a whole and the definition of all the steps of a procedure for the evaluation of the safety of a building.

On-Site Identification of Pottery with pXRF: An Example of European and Chinese Red Stonewares

The invention of European hard porcelain, which aims at imitating kaolin-containing white paste of Chinese porcelain, had been started by the development of the technology of “red porcelain”, so-called “Jaspisporzellan” by Johann Friedrich Böttger in the early-eighteenth century at Meissen (Saxony). The visual features of the earlier Böttger red stoneware were rather similar to the one produced in Yixing, China. The prominence of Böttger productions allowed the manufacturing to be expanded across Europe to different countries (Holland, England, France, etc.). In this study, the chemical characteristics of nine European unglazed objects produced in England, France, Russia, and Holland from the 17th to 19th century and 10 Chinese (unglazed or enameled) red stoneware have been studied by using an on-site characterization technique pXRF. The results were compared with the previous studies carried out on 25 unglazed, polished, and non-polished Böttger artefacts. This non-invasive, speedy technique allows a methodology to be created for distinguishing the technological differences related to the provenance and authenticity of the artefacts. The elemental measurements explicitly show the significant discrepancy of Dutch objects from the main group, which involves other European and Chinese ones. Both a Lambertus van Eenhoorn (Delft) statue and an Ary de Milde (Delft) teapot are distinguishable from other European red stoneware by the high content of iron and calcium and high content of titanium and potassium, respectively, found in their body compositions. An overall comparison was made between the measurements made at different times in order to evaluate the error range arising from the measurement procedure (e.g., energy resolution of other series of the same instrument model).

A Custom-Made Lower Limb Dynamometer for Assessing Ankle Joint Torque in Humans: Calibration and Measurement Procedures

Custom-made dynamometry was shown to objectively analyze human muscle strength around the ankle joint with accuracy, easy portability and low costs. This paper describes the full method of calibration and measurement setup and the measurement procedure when capturing ankle torque for establishing reliability of a portable custom-built electronic dynamometer. After considering the load cell offset voltage, the pivotal position was determined, and calibration with loads followed. Linear regression was used for calculating the proportionality constant between torque and measured voltage. Digital means were used for data collection and processing. Four healthy consenting participants were enrolled in the study. Three consecutive maximum voluntary isometric contractions of five seconds each were registered for both feet during plantar flexion/dorsiflexion, and ankle torque was then calculated for three ankle inclinations. A calibration procedure resulted, comprising determination of the pivotal axis and pedal constant. Using the obtained data, a measurement procedure was proposed. Obtained contraction time graphs led to easier filtering of the results. When calculating the interclass correlation, the portable apparatus demonstrated to be reliable when measuring ankle torque. When a custom-made dynamometer was used for capturing ankle torque, accuracy of the method was assured by a rigorous calibration and measurement protocol elaboration.

Design and Application of a New Artificial Intelligence Screening Program for Scoliosis

Objective — Intelligent Scoliosis screening Application (ISSAPP) is an intelligent scoliosis screening application based on back photos, which is used to determine the effectiveness and reliability of the new tool and reduce the cost of screening by comparing it with traditional physical examination. Method — To design and upgrade the measurement procedures for back photographs during physical examination, including the measurement of bilateral shoulder apex line and horizon plus angle, and the measurement of the angle between the thoracic apex line and horizon during Adams' spinal flexion experiment so as to determine the validity and reliability of measurement program tools. Results — The first and second versions of the designed AI measurement program were more sensitive than the traditional physical examination, Adams spinal flexion test, and lateral flexion instrument. The majority of patients who were tested positive using the measurement procedure tool met the requirements for diagnosis of scoliosis. Conclusions — This new AI based measurement and screening tool can be used for early detection of shoulder and thoracic malformation caused by scoliosis, which is a simple, convenient and sensitive early screening tool. Based on this development idea, an upgraded version can be further developed for early screening of scoliosis.

Study of the heat capacity of VZhM4 nickel superalloy using differential scanning calorimetry, adiabatic and mixing calorimetry

An increase in the operating temperatures of assemblies and parts of modern aircraft is a key task for the aviation industry which entails developing of new materials that meet the increased requirements for their operational characteristics. A high level of the accuracy and reliability of the determined properties is one of the most important factors in designing high-temperature metal, ceramic and heat-shielding materials. The features of a particular measurement procedure, as well as their hardware design, do not always ensure the specified accuracy of experiments over the entire temperature range. We present the results of studying the heat capacity of VZhM4 nickel superalloy in the temperature range 100 – 1360° C by the methods of differential scanning calorimetry (DSC), adiabatic and mixing calorimetry. The data of the DSC analysis of the alloy, the temperatures of phase transformations and temperature dependences of the specific heat of the material are analyzed along with the assessment of their accuracy at different temperature intervals. A comparative analysis of the studied measurement procedures complements the research. The results obtained can be used in the development of new materials and in the study of the specific heat capacity of metal products in a wide temperature range.