Location Of Measurement Points Research Articles

Thermal characteristics of ghosting flame in coal mine dead-end roadway pool fires affected by fire locations

As an important phenomenon in the evolution of fire, the ghosting flame exhibits dynamic and irregular behavior in environments with limited ventilation. By ghosting flame, we mean the phenomenon where the flame separates from the fuel surface under certain conditions. This study investigates the combustion characteristics of the ghosting flame in pool fires within a coal mine dead-end roadway by small-scale experiments. Results indicate that the ghosting flame appears more readily and earlier when the fire source is closer to the heading face or when the oil pan size is larger. Additionally, the fire source's location significantly influences the type of ghosting flame observed. When the fire source is near the heading face, the flame predominantly exhibits horizontal-type ghosting flame; however, when the fire source is at the entrance of the roadway, only the edge-type ghosting flame occurs. Furthermore, dead-end roadway fires easily transition to ventilation-controlled conditions, leading to a continuous increase in the mass loss rate. The occurrence of a ghosting flame does not result in a sudden change in the mass loss rate. Moreover, the transient oxygen volume fraction when the ghosting flame occurs is related to the ghosting flame type and is also affected by ventilation conditions, fuel types, roadway structure, and the location of measurement points. Importantly, the root cause for the occurrence of the ghosting flame lies in the pressure differential generated by the temperature disparity between the two sides of the fire source.

Modeling and Optimization of NO2 Stations in the Smart City of Barcelona

The growing problem of nitrogen dioxide (NO2) pollution in urban environments is driving cities to adopt smart and sustainable approaches to address this challenge. To quantify and compare the effect of environmental policies, cities must be able to make informed decisions with real-time data that reflect the actual situation. Therefore, the objective of this work is threefold: The first is to study the behavior of the key performance indicator (KPI) of NO2 concentrations per station in Barcelona through exploratory analysis and clustering. The second is to predict NO2 concentration behavior, considering meteorological data. Lastly, a new distribution of current and new stations will be proposed using an optimization algorithm that maximizes the distance between them and covers the largest area of the city. As a result of this study, the importance of the location of measurement points and the need for better distribution in the city are highlighted. These new spatial distributions predict an 8% increase in NO2 concentrations. In conclusion, this study is a comprehensive tool for obtaining an accurate representation of NO2 concentrations in the city, contributing to informed decision-making, helping to improve air quality, and promoting a more sustainable urban environment.

Monitoring of thick-walled pressure elements to determine transient temperature and stress distributions using the measured fluid's pressure and wall's temperature

The paper presents a new stress monitoring method for cylindrical pressure elements of the power unit. It can be used to monitor a power unit's start-up, shutdown, and load change to reduce the unit's connection time to the power grid. The outer surface of the component is thermally insulated. Circumferential thermal stress at the point of its concentration at the hole edge is determined based on the stress determined at a greater distance from the hole. The circumferential thermal and pressure stresses at the hole edge are calculated by multiplying the stress values determined for the non-weakened wall by the respective concentration factors. In addition, the heat transfer coefficient (HTC) at the inner surface of the pressure element is necessary to determine the thermal stress concentration factor. Heat transfer correlations available in the literature are used to calculate HTC. The transient element wall temperature is measured five to 12 mm from the inner surface of the cylindrical component. An analysis of the measurement point locations on the accuracy of temperature and stress determining at the inner component surface was investigated. A practical application of the proposed method using real measurement data is presented.

Optimizing the uncertainty of measurements on a coordinate measuring machine when controlling complex geometric surfaces

The object of this study is the process of optimizing measurement uncertainty on a coordinate measuring machine (CMM) when inspecting complex geometric surfaces. The problem addressed was insufficient accuracy and efficiency of measurements of complex parts on CMMs under production conditions. A method for optimizing measurement uncertainty has been devised, which includes a mathematical model of the measurement process and an adaptive algorithm for optimizing the control strategy, based on the Monte Carlo method. The model takes into account the geometry of surfaces and CMM characteristics, while the algorithm dynamically adjusts measurement parameters. The results demonstrate a reduction in measurement uncertainty by 15–20 % and a reduction in inspection time by 10–12 % compared to conventional methods. This is achieved by taking into account the specificity of complex surface geometry and an adaptive approach. The uniqueness of the developed method is the ability to automatically adapt to different types of CMMs and measured objects, optimizing the number and location of measurement points, the speed of probe movement, and its contact force with the surface. The method takes into account not only the geometric parameters of objects but also the characteristics of the CMM itself, which allows for high accuracy. The method is particularly effective for parts with complex geometry, in which conventional methods often lead to significant errors. Practical application is possible at machine-building enterprises for quality control of complex parts, especially in serial production. The implementation of the developed method allows for improving product quality and reducing production costs by 8–10 % due to optimization of the control process and reduction of defects

The usage of interference effects in single Guided Ultrasonic Wave time signals for damage identification

Guided Ultrasonic Waves (GUW) interact with structural inhomogenities in multiple ways, e.g. mode conversions, mode scattering, oscillation phase shifts and reflections. These effects do occur at specimen edges and at damage on and in the specimen’s area. These effects at structural boundaries make the signal interpretation more complex. On the other hand they can lead to additional information in recorded time signals when caused by damage. This study aims at the usage of interference effects in single time signals caused by damage in the structure. This is investigated changing the location of the measurements points in relation to the damage position. Two cases are taken into account: once the damage lies in the direct measurement patch between actuator and measurement point and once the damage lies outside the measurement path and its effect on the recorded time signal is investigated. In the experimental setup, a rectangular Aluminum plate is used. Its dimension is chosen to make sure that edge reflections do not superimpose with the regarded wave packages within the time signals. A Laser-Doppler-Vibrometer allows the non-contact recording of several measurement points and is not wavelength-dependent as e.g. PZT-transducers. This allows the measurement to be unaffected by the transfer behavior of the transducers. The relationship between the specific mode wavelength reflected by the damage and the measurement path length provides information about the expected level of interference at the considered measurement point. The anticipation includes the indirect identification of damage off the direct measurement path through the observed interference effects, as well as variations in interference caused by the shift of the measurement point locations. The amplitude and phase changes serve as a measure of the interference and are obtained using the Hilbert transform.

Research on the location of measurement points in explosion shock wave pressure testing

Shock wave is an important damage element in ammunition explosion and one of the important technical indicators for evaluating its damage power. Accurately measuring shock wave pressure is of great significance for guiding ammunition design and evaluating damage power. The testing environment in the explosion field is harsh, and the measurement of shock wave pressure is affected by various influencing factors, resulting in inaccurate measurement results and low reliability. The location of pressure measurement points directly affects the measurement results of surface reflection pressure and free field pressure. This study is based on the display explosion dynamics simulation software AUTODYN to conduct simulation analysis of the propagation law of explosion shock wave pressure, analyze the height variation of the three wave point trajectory during the ammunition explosion process, and clarify that the surface reflection pressure measurement points need to be located in the Mach reflection zone, and the free field pressure measurement points need to be located above the height of the three wave points. The research results provide theoretical support for accurate testing of explosion shock wave pressure and have significant engineering application value.

The calibration of sharp-crested weirs with a horizontal edge used for measuring flows in partially full pipes

This paper presents the results of a laboratory study on the discharge capacity of sharp-crested weirs fitted with a horizontal edge in pipes during open-channel flow conditions and clean water used to measure the outflow. Such sharp-crested weirs are mounted in pipes and are used to control the inflow to separators. The stream profile does not correspond to the profile given by Bazin for sharp crested weirs in channels. A desired location of the water level measurement point for flow rate calculations was provided. Discharge curves were identified for three sharp-crested weirs of 0.0465, 0.0634 and 0.0771 m in height, installed in the pipe of 0.1534 m in diameter and inclinations of 0.5 and 1.0%. The discharge curves for weir flow with free nappe does not show a significant effect of the pipe slope on the weir discharge capacity. The non-dimensional formulas for the discharge capacity of the sharp-crested weir were found as general polynomial regressions. The results indicate that the calibrated sharp-crested weir with a horizontal edge placed in a pipe can be used to control the flow. Due to the scale effect, relationships obtained from the calibration cannot be generalised to other pipe diameters and weirs heights than those analysed.

Research on multi-physical field analysis and assessment technique of virtual connection defects in cluster cable joints based on digital twin technology

As the “blood vessels” and “nerves” of the power grid, cables are important carriers for transmitting electric energy, and their failures will affect the safe and stable operation of the power grid. In this paper, a digital twin model of thermal characteristics is constructed for 10 kV YJV×400 cluster cable and its joint model. Based on the multi-physical field coupling analysis method, the fluid field, temperature field and current-carrying capacity of the cluster cable are analyzed. The temperature rise and airflow distribution characteristics of the joint and its external insulation when the defect of joint false connection occurs are analyzed. Based on the fuzzy analytic hierarchy process (FAHP), weights are assigned to the locations of multiple measurement points of the cable external insulation, and the temperature distribution of each measurement point is combined with the digital twin technology to calculate the hot spot temperature of the cable, so as to assess the defects of the joints of the cables. The digital twin platform is used for real-time monitoring of cable status and assessment of defects. The temperature rise experiments of cables under different carrying capacity and joint defects show that this method can accurately and efficiently calculate hot spot temperatures and assess defects of joints in cluster cables.

Automatic Acquisition System for Mine Pressure Monitoring in Coal Mine Working-Face Footage

The existing mine pressure monitoring system has realized the online continuous monitoring of the working-face stent resistance, roadway roof offcuts, and anchor rod/rope working resistance. However, the mine pressure monitoring information of the working face currently includes only the stent resistance and the monitoring time, and there is no information on the working-face advance. The mine pressure data cannot be precisely analyzed due to a lack of measurement point locations. Mine pressure data analysis combined with the working-face feed information is the basis for safe and efficient mining and for improving the intelligence level of the comprehensive mining face. According to the special electromagnetic environment of the underground, this system adopts UWB (ultra-wide-band) technology and the SDS-TWR (symmetric double-sided two-way ranging) ranging method, with the UWB positioning base station as the core and installs positioning tags at the end supports of the working face to collect information. The data are uploaded to the host computer via Ethernet for coordinate solving, automatically collecting the working-face footage data and providing positional information for mine pressure monitoring. The application results show that the system operates normally and can collect real-time information of working-face footage and monitor mine pressure data, and meet the requirements of coal mine positioning accuracy, positioning error is less than 30 cm, the application effect is good.

Human Body as a Signal Transmission Medium for Body-Coupled Communication: Galvanic-Mode Models

Signal propagation models play a fundamental role in radio frequency communication research. However, emerging communication methods, such as body-coupled communication (BCC), require the creation of new models. In this paper, we introduce mathematical models that approximate the human body as an electrical circuit, as well as linear regression- and random forest-based predictive models that infer the expected signal loss from its frequency, measurement point locations, and body parameters. The results demonstrate a close correspondence between the amplitude-frequency response (AFR) predicted by the electrical circuit models and the experimental data gathered from volunteers. The accuracy of our predictive models was assessed by using their root mean square errors (RMSE), ranging from 1.5 to 7 dB depending on the signal frequency within the 0.05 to 20 MHz range. These results allow researchers and engineers to simulate and forecast the expected signal loss within BCC systems during their design phase.

Analysis of the Usefulness of Measurement on a Board at Ground Level for Assessing the Noise Level from a Wind Turbine

The specific working conditions of the wind turbine in strong wind cause a number of problems in the measurement of noise indicators used in its short and long-term assessment. The wind is a natural working environment of the turbine, but it also affects the measurement system, moreover, it can be a secondary source of other sounds that interfere with the measurement. One of the effective methods of eliminating the direct impact of wind on the measurement system is placing the microphone on the measurement board at ground level. However, the obtained result can not be directly compared with the admissible values, as it has to be converted to a result at a height of 4 m. The results of previous studies show that this relation depends, inter alia, on the speed and direction of the wind. The paper contains the results of measurements on the measurement board, according to EN 61400-11:2013, and at a height of 4 m above ground made simultaneously in three points around the 2 MW turbine at various instantaneous speeds and changing wind directions. Analysis of the impact of measuring point location on the measurement result of noise indicators and the occurrence of additional features affecting the relationship between the values measured on the board and at the height of 4 m, and especially the tonality, amplitude modulation and content of low frequency content, was made.

Role of rivers in restricting pollution movement, as evidenced by chemical and isotopic research on the Widawa River in Wrocław (SW Poland)

This article presents results of chemical and isotopic studies of shallow groundwater and surface waters in order to determine the degree of their contamination near to artificial irrigation fields. The study applied the methodology of detailed sampling around the river in order to capture the direction of pollutant flow and to determine the state of the environment. Samples were taken on both sides of the river, from its bottom and directly from the river. Thanks to bottom pressure measurements, it was possible to determine in what section the river drains or infiltrates groundwater, which, combined with chemical and isotope analyses, made it possible to determine the aims of this study. As it turns out, the nature of the river in the study area is mainly neutral and in lesser extent draining, which does not translate into the degree of groundwater pollution at every point. Due to the sampling methodology used, it was also possible to determine the depth of redox processes and the origin of sulfur in water, which comes mainly from precipitation and other anthropogenic sources. Chemical tests indicate an average quality of shallow groundwater, anthropogenically transformed to varying degrees depending on the location of measurement point. These preliminary results support the applicability of this sampling methodology to other studies and indicate the need to perform more detailed chemical analysis.

The dependence of transformer sound power measurement accuracy on microphone configurations in the anechoic chamber.

The paper is aimed at investigating the number and location of microphones required to accurately calculate the sound power level of a harmonic noise source. The measurement procedure performed is based on the IEC standard for the determination of transformer sound power level. The current procedure defines numerous measurement points around the tested transformer. Reducing the number of measurement points could significantly speed up the measurement procedure when a transformer is tested during the manufacturing process. Within the research work, estimations on the number and location of measurement points are identified to accurately calculate sound power level. The approach is tested and validated using specially developed software in LabView, that allows inclusion or exclusion of measurement points from the sound power level calculations. To prevent harmonic wave interference, acoustic wave reflections and background noise, the measurement procedure took place in the anechoic chamber.

Genetic parameters and genome-wide association study of digital cushion thickness in Holstein cows.

The digital cushion is linked to the development of claw horn lesions (CHL) in dairy cattle. The objectives of this study were to (1) estimate genetic parameters for digital cushion thickness (DCT), (2) estimate the genetic correlation between DCT and CHL, and (3) identify candidate genes associated with DCT. A cohort of 2,352 Holstein dairy cows were prospectively enrolled on 4 farms and assessed at 4 time points: before calving, immediately after calving, in early lactation, and in late lactation. At each time point, CHL was recorded by veterinary surgeons, and ultrasonographic images of the digital cushion were stored and retrospectively measured at 2 anatomical locations. Animals were genotyped and pedigree details extracted from the national database. Genetic parameters were estimated following a single-step approach implemented in AIREMLF90. Four traits were analyzed: the 2 DCT measurements, sole lesions (sole hemorrhage and sole ulcers), and white line lesions. All traits were analyzed with univariate linear mixed models; bivariate models were fit to estimate the genetic correlation between traits within and between time points. Single-marker and window-based genome-wide association analyses of DCT traits were conducted at each time point; candidate genes were mapped near (<0.2 Mb) or within the genomic markers or windows with the largest effects. Heritability estimates of DCT ranged from 0.14 to 0.44 depending on the location of DCT measurement and assessment time point. The genetic correlation between DCT and sole lesions was generally negative, notably between DCT immediately after calving and sole lesions in early or late lactation, and between DCT in early or late lactation and sole lesion severity in early or late lactation. Digital cushion thickness was not genetically correlated with white line lesions. A polygenic background to DCT was found; genes associated with inflammation, fat metabolism, and bone development were mapped near or within the top markers and windows. The moderate heritability of DCT provides an opportunity to use selective breeding to change DCT in a population. The negative genetic correlation between DCT and sole lesions at different stages of production lends support to current hypotheses of sole lesion pathogenesis. Highlighted candidate genes provide information regarding the complex genetic background of DCT in Holstein cows, but further studies are needed to explore and corroborate these findings.

Modeling nutrient removal and energy consumption in an advanced activated sludge system under uncertainty

Activated sludge models are widely used to simulate, optimize and control performance of wastewater treatment plants (WWTP). For simulation of nutrient removal and energy consumption, kinetic parameters would need to be estimated, which requires an extensive measurement campaign. In this study, a novel methodology is proposed for modeling the performance and energy consumption of a biological nutrient removal activated sludge system under sensitivity and uncertainty. The actual data from the wastewater treatment plant in Slupsk (northern Poland) were used for the analysis. Global sensitivity analysis methods accounting for interactions between kinetic parameters were compared with the local sensitivity approach. An extensive procedure for estimation of kinetic parameters allowed to reduce the computational effort in the uncertainty analysis and improve the reliability of the computational results. Due to high costs of measurement campaigns for model calibration, a modification of the Generalized Likelihood Uncertainty method was applied considering the location of measurement points. The inclusion of nutrient measurements in the aerobic compartment in the uncertainty analysis resulted in percentages of ammonium, nitrate, ortho-phosphate measurements of 81%, 90%, 78%, respectively, in the 95% confidence interval. The additional inclusion of measurements in the anaerobic compartment resulted in an increase in the percentage of ortho-phosphate measurements in the aerobic compartment by 5% in the confidence interval.The developed procedure reduces computational and measurement efforts, while maintaining a high compatibility of the observed data and model predictions. This enables to implement activated sludge models also for the facilities with a limited availability of data.

The Influence of Rainfall and Evaporization Wetting-Drying Cycles on the Slope Stability

The decay of soil strength and the change of soil infiltration characteristics caused by the dry and wet cycle effect generated by the rainfall-evaporation process are important factors that induce slope instability. How to consider the effect of soil strength decay and water-soil characteristic curve hysteresis effect on transient stability change of slope is the key to solve this problem. In this paper, transient stability analysis of slopes considering soil strength decay and water-soil characteristic curve hysteresis is carried out based on Geo-Studio. The results of the study showed that the change of transient safety factor of the slope caused by rainfall-evaporation dry and wet cycle process has an overall decreasing trend and the safety factor decreased by 43% compared to the initial state. The seepage characteristics of the rainfall-evaporation dry-wet cycle have certain regularity. The location of slope measurement points has a greater influence on the magnitude of the pore pressure change: foot of slope &gt; middle of slope &gt; top of slope. Also, there is a significant response hysteresis in the change of pore pressure with increasing depth at the same location. The rainfall intensity has a certain influence on the change of slope safety factor, but its influence is not obvious when the rainfall intensity exceeds a certain amount.

Existence and Uniqueness Theorems in the Inverse Problem of Recovering Surface Fluxes from Pointwise Measurements

Inverse problems of recovering surface fluxes on the boundary of a domain from pointwise observations are considered. Sharp conditions on the data ensuring existence and uniqueness of solutions in Sobolev classes are exposed. They are smoothness conditions on the data, geometric conditions on the location of measurement points, and the boundary of a domain. The proof relies on asymptotics of fundamental solutions to the corresponding elliptic problems and the Laplace transform. The inverse problem is reduced to a linear algebraic system with a nondegerate matrix.

Using Thermal Monitoring and Fibre Optic Measurements to Verify Numerical Models, Soil Parameters and to Determine the Impact of the Implemented Investment on Neighbouring Structures

Numerical modelling using Finite Element Method (FEM) is currently a standard procedure for engineering complex structures and determining structure–subsoil cooperation conditions. It is used for, among others, forecasting displacements, which are the calculation results most easily verified. Numerical modelling is also used to identify the impact on neighbouring structures and design a monitoring system and determine expected values, e.g., displacements. A numerical model enables one to optimally design the monitoring system for a facility under construction and the neighbouring structures through selecting a measurement technology, matching the scope of obtained results or choosing sensor and measurement point locations. The implemented monitoring may be based on various technologies, from thermal monitoring, laser scanning, fibre optic measurements, to classic surveying measurements. The walls must protect the soil from excessive displacement and protect the excavation against groundwater inflow. If the wall is not watertight, deepening the excavation may cause a sudden water inflow. Leak and erosion process thermal monitoring is a proven leak detection method. It is based on the tests utilizing heat and water transfer process relations, which are coupled processes. Another tool for verifying numerical models is the installation of DFOS (Distributed Fibre Optic Sensors) at the stage of executing structural elements (e.g., diaphragm walls, barrettes, foundation slab). It allows one to permanently monitor both temperature and displacements during element execution (concrete curing), and following facility construction and operation stages. The paper presents methods for designing selected monitoring elements of engineering objects, based on calculations using the Finite Element Method. The verification of numerical models, based on data obtained from DFOS, classic surveying measurements and thermal monitoring, is also presented.

An improved sequential function specification coupled with Broyden combined method for determination of transient temperature field of the steel billet

Accurate knowledge of the steel billet temperature field in the reheating furnace is of crucial importance to improvement of product quality and energy conservation. For this purpose, the determination of the transient temperature field of the steel billet during reheating is investigated based on the inverse heat conduction problem. The transient two-dimensional heat transfer model of the billet in the furnace is established and used as the direct problem. The sequential function specification coupled with the Broyden combined method (BC-SFSM) is developed to obtain the temperature field of steel billet. A real measurement experiment is conducted for validation of the inverse model, which indicates that the BC-SFSM can accurately determine the billet temperature field from the temperatures measured at three points inside the billet. A series of numerical experiments are implemented to analyze the performance of the BC-SFSM and study the effects of the measurement point locations and of the number of future time steps on inverse results. The results illustrate that the BC-SFSM can take only 49.0% of the computing time of the sequential function specification method to estimate the billet temperatures, and the relative root-mean-square error of estimated temperatures is generally less than 1.5% when the reasonable number of future time steps and suitable measurement point locations are adopted. Therefore, the BC-SFSM in this work is a promising algorithm to determine the billet temperature field in the reheating furnace with high accuracy and efficiency.

On the Breathability Measurement of Surgical Masks: Uncertainty, Repeatability, and Reproducibility Analysis

Wearing protective face mask has been demonstrated as one of the most effective COVID-19 prevention measures. The breathability measurement of surgical masks is normed by the UNI EN 14863:2019. This study aims at evaluating the uncertainty and reproducibility in the breathability ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta P$ </tex-math></inline-formula> ) measurement, as well as understanding the effects induced by the number and location of the measurement points. A total of 300 surgical masks were tested for breathability. For each mask, 15 measurement points have been considered. Results showed that more than 60% of the tested masks do not satisfy the standard requirements in terms of breathability, with the lower percentage of compliant mask associated with type II. Repeatability was found comparable to the instrument uncertainty related to the digital resolution of the device. A relative percentage variability related to the reproducibility up to 21.2% was found for the mask type II, thus allowing to affirm that different areas of the same mask can lead to different results in terms of breathability. The reproducibility error was found as the main source of uncertainty, leading to an underestimation or overestimation of the breathability value and, consequently, of the number of compliant masks. Finally, the number and location of measurement points represent a further source of uncertainty influencing the final value of the breathability also among the masks produced by the same manufacturer.