Measurement Accuracy Research Articles

Evaluating the Impact of Sample Irregularities on the Dynamic Stiffness of Polyurethane: Insights from Experimental and FEM Analysis

This study investigates the dynamic stiffness and damping characteristics of three polyurethane materials—PM, PS, and PST—using a comprehensive vibroacoustic testing approach. The aim is to examine material parameters such as dynamic stiffness, Young’s modulus, critical damping factor, and the influence of sample irregularities on the accuracy of measurements. The study employs both experimental testing, in which cuboidal and cylindrical polyurethane samples were subjected to sinusoidal excitation, and finite element modeling (FEM) to simulate the test conditions in sample without irregularities. Results indicate that sample contact surface irregularities (even as low as ~0.04 mm) significantly impact the measured dynamic stiffness, with the effect intensifying for materials with higher Young’s modulus values (above 5 MPa). Furthermore, cylindrical samples demonstrated more stable and repeatable measurements compared to cuboidal samples, where surface irregularities were tested in a more controlled environment. The findings underscore the need to consider sample geometry and irregularities in dynamic stiffness assessments to ensure better material evaluations. This work contributes valuable insights for the accurate modeling and testing of materials used in vibration isolation and sound insulation contexts.

Subaperture moving strategy and related systematic errors in stitching interferometry of X-ray mirrors

For high-precision metrology of X-ray mirrors, the subaperture moving strategy significantly impacts the accuracy of stitching interferometry. In this work, we investigated the systematic errors associated with various subaperture moving strategies of rotational stitching (RS), rotational displacement stitching (RDS), and displacement stitching (DS) in measuring X-ray mirrors. The effects of stitching strategies on a flat mirror and a spherical mirror with a radius of curvature (RoC) of 180 m and 60 m were compared. For the mirror with RoC of 60 m, the DS strategy showed the smallest height error of 3.3 nm (RMS) between algorithm-based stitching and the Nanometer Optical component Measuring machine (NOM), while RS showed a large error of 37.4 nm (RMS). The different regions of the interferometer aperture have different amplitudes of retrace errors, defocusing errors, and lateral distortion, which can lead to accumulations of systematic errors using the RS strategy. By reducing the pixel size from 0.268 mm/pixel to 0.089 mm/pixel, the measurement accuracy using the same RDS strategy improved from 7.4 nm (RMS) to 4.4 nm (RMS). Based on the optimal stitching strategy, the measurement accuracy of residual figure error of the X-ray mirror with a radius of curvature of 30 m reaches 0.2 nm (RMS).

Uncertainty and worst-case expectation analysis for multiphysics QPR simulations

Abstract Quadrupole resonators (QPRs) serve to characterize superconducting samples. Like any cavity, during operation, they will deviate from the design geometry for various reasons. Those deviations can be static, stemming from manufacturing variations reflected in the manufacturing tolerances, or dynamic, such as electromagnetic radiation pressure (Lorentz detuning) or microphonics. As a result, a QPR's measurement accuracy and general operation can be severely limited. In particular, during operation, it became evident that the third operating mode of typical QPRs is mainly affected. In this work, by solving the underlying multiphysics problem with random input parameters, we predict the predominant sources of significant measurement bias in surface resistance. On the one hand, we employ the stochastic collocation method compound with the polynomial chaos expansion (PC-SCM) to quantify uncertainties in the physical model governed by a coupled electro-stress-heat (E-S-H) problem. On the other hand, we explore the perturbation analysis to calculate the mean-worst-scenario bound of the merit functions due to the first-order truncation of the Taylor expansion around mean parameter values. The developed method allows us to study the effect of a small nonlinear deformation on the performance of the QPR. Finally, we discuss the simulation results and their implication for the operational conditions of the QPRs.

Diary- and actigraphy-estimated nighttime sleep during the perinatal period: A multimethod study.

Accurate estimation of perinatal sleep is important for informing future research and multigenerational health interventions. We compared diary- and actigraphy-estimated sleep parameters during pregnancy and postpartum. We informed our interpretation of these analyses with participants' feedback about these sleep estimation methods. This preregistered study ( https://doi.org/10.17605/OSF.IO/UZFRD ) included 92 English-speaking, women-identified birthing parents who completed sleep diaries and wore wrist actigraphs for 7days during the 3rd trimester of pregnancy, 6weeks postpartum, and 16weeks postpartum. Sleep parameters included total sleep time (TST), sleep efficiency (SE), sleep onset latency (SOL), and wake after sleep onset (WASO). Multilevel models tested associations between diary and actigraphic sleep over time. Results indicated that diary and actigraphic sleep parameters were significantly associated over time, although actigraphic TST, SE, and SOL tended to be lower-and WASO longer-than diary estimations. WASO estimations were significantly more discrepant during 6weeks postpartum than during the 3rd trimester or 16weeks postpartum. Using conventional content analysis, three primary themes emerged from participants' feedback about sleep diaries and wrist actigraphs that enriched our interpretation of multilevel model results: (1) Wearability, (2) Functionality/Ease of Use, and (3) Measurement Accuracy. This study was the first to implement a multimethod design supplemented by qualitative data to investigate not only the association between diary and actigraphic perinatal sleep, but what it is like for birthing parents to engage with these sleep estimation methods. This study has important implications for behavioral medicine research and practice with perinatal populations.

The compact beam energy measurement method of the photocathode RF gun by the solenoid and beam shaping.

Beam energy, normalized emittance, and quantum efficiency are crucial parameters of the RF gun. In this study, we proposed a compact and low-cost method to measure the beam energy at the exit of the 120 MeV electron linac's RF gun. We utilized a solenoid magnetic field to rotate an elliptical beam and measured the rotation angle of the beam to calculate the energy. To generate an elliptical electron beam, we inserted a slit device after the laser beam shaping aperture (BSA) to produce a long strip of driving laser beam for the RF gun photocathode. During the measurement process, we employed the Maximally Stable Extremal Regions (MSER) detection algorithm to measure the beam spot angle, improving the accuracy and stability of the angle measurement. This method does not require any changes to the accelerator lattice, nor does it require additional space. It only requires inserting a slit device to measure the beam's energy. Our results indicated that the energy at the exit of the RF gun was 4-5 MeV, consistent with simulation calculations using ASTRA.

Angle Expansion Estimation and Correction Based on the Lindeberg–Feller Central Limit Theorem Under Multi-Pulse Integration

The radar monopulse angle measurement can obtain a target’s angle information within a single pulse, meaning that factors such as target motion and amplitude fluctuations, which vary over time, do not affect the angle measurement accuracy. However, in practical applications, when a target’s signal-to-noise ratio (SNR) is low, the single pulse signal is severely affected by noise, leading to a significant deterioration in angle measurement accuracy. Therefore, it is usually necessary to coherently integrate multiple pulses before estimating the angle. This paper constructs an angle expansion model for a multi-pulse angle measurement under coherent integration. The analysis reveals that even under noise-free conditions, after coherently integrating multiple pulses, the coupling of target amplitude fluctuations and motion state can still cause significant errors in the angle measurement. Subsequently, this paper conducts a detailed analysis of the impact of the amplitude fluctuations and target maneuvers on the random angle measurement error. It also derives approximate probability density functions of angle measurement errors under various fluctuation and motion scenarios based on the Lindeberg–Feller central limit theorem. In addition, based on the angle expansion model and the random error distribution, this paper proposes an angle correction algorithm based on multi-pulse integration and long-term estimation. Numerical experiments and radar data in the field verify the impact of target characteristics on the angle measurement under multi-pulse integration and the effectiveness of the angle correction algorithm.

Pure rotational Raman lidar for accurate profiling of atmospheric temperature and aerosol/cloud backscatter coefficients

We have created a pure rotational Raman (PRR) lidar for round-the-clock and large-height-range quantitatively-physical measurements of atmospheric temperature profiles. A seeded frequency-doubled Nd:YAG laser is utilized as the light source. It has a typical power of ∼18 W and a pulse repetition rate of 30 Hz. The lidar uses a 0.3-m-diameter receiver and a 1.0-m-diameter receiver together. Each receiver contains a state-of-the-art three-channel polychromator that extracts respectively two individual Stokes N2 PRR lines with rotational quantum numbers J = 4 and 14, as well as a Rayleigh/Mie backscatter signal. The temperature profiles are derived from the strict analytical expression of temperature in terms of the ratio of the two PRR line signals without calibration. Furthermore, a strict analytical expression has been established to derive the aerosol/cloud backscatter coefficient profiles without assumptions on the lidar ratio. The lidar provides a rigorous and effective methodology for accurate profile measurements of the atmospheric temperature and optical properties of aerosol/cloud. Observational examples and statistics obtained at a subtropical site have demonstrated the high measurement accuracies, large measurement altitude range, good range/time resolution, and unprecedented daytime measurement capability of this single-line-extracted PRR lidar.

Comparative analysis of smartphone colorimeter apps and spectrophotometry for measuring forehead skin color in maxillofacial prosthesis fabrication.

This study aimed to evaluate the accuracy and precision of two smartphone colorimeter apps, Color Grab, and Color Picker, in measuring forehead skin color and to compare their readings with those from a spectrophotometer. Fifty participants (26 males, 24 females; median age 23 years, range 21-45) were included. Using a smartphone camera, images of forehead skin were captured, and CIELAB color values were reported by both apps. Measurements from a reference spectrophotometer (MiniScan EZ 4500L, 45°/0° geometry) served as the gold standard. Trueness and precision were assessed using CIELAB and CIEDE2000 formulas. Statistical analyses included one-way ANOVA and Mann-Whitney tests, with significance at p<0.05. Both apps showed comparable accuracy in capturing skin color, with absolute trueness (ΔEAbs) for Color Grab at 7.59 (CIEDE2000) and Color Picker at 7.65. Relative trueness (ΔERel) was 3.79 for Color Grab and 3.70 for Color Picker. Precision (MCDM) demonstrated significant differences between the apps: Color Grab at 1.34 (CIEDE2000) compared to Color Picker at 0.96 (p<0.0001). While smartphone apps may not match the accuracy of spectrophotometers, they offer valuable alternatives for color matching in maxillofacial prostheses. Future studies should focus on minimizing systematic errors related to environmental factors and camera settings to enhance measurement accuracy.

Smartphone scanning is a reliable and accurate alternative to contemporary residual limb measurement techniques.

Monitoring the volume and shape of residual limbs post-amputation is necessary to achieve optimal socket fit and determine overall limb health, yet contemporary clinical measurement techniques show high variance between measures. Three-dimensional scanning presents an opportunity for improved accuracy and reliability of residual limb measurements, however, three-dimensional scanners remain prohibitively expensive. A cost-effective alternative is the use of software that can utilise the photographs of modern smartphone cameras to create geometrically accurate scans. Whilst several studies have investigated the potential of privately developed photogrammetry algorithms for capturing residual limbs with clinical accuracy, none to the authors knowledge have explored commercially available software to do the same. Three applications were tested, namely Polycam, Luma, and Meshroom, to determine if they could produce clinically acceptable results. Scans of ten residual limbs were created using both smartphone technology and a reference structured-light scanner (Artec EVA), against which the validity and reliability of the resulting limb models were assessed using the Bland-Altman method and Intraclass Correlation Coefficient, respectively. Polycam and Luma achieved both Pearson Coefficients and Intraclass Correlation Coefficients of 0.999, and Coefficients of Variation of 1.1% and 1.4%, respectively. Volume reliability coefficients were 58.3 ml and 70.0 ml respectively for Polycam and Luma, whereas Meshroom failed to meet any of the criteria for clinical suitability, with a repeatability coefficient of 790.3 ml. Both Polycam and Luma exhibit sufficient accuracy and reliability to be considered for clinical volume measurements.

Spectroscopic ellipsometry utilizing frequency division multiplexed lasers

Spectroscopic ellipsometry (SE), which measures the thickness of thin films in a non-contact way with an accuracy of angstroms, has been widely used for optical metrology. Several types of SE are available both commercially and in research, although they require specific implementations depending on the application. Here, we theoretically and experimentally demonstrate the Frequency Division Multiplexing Spectroscopic Ellipsometry (FDM-SE) technique. With respect to conventional rotating polarizing element ellipsometry, our variant uses discrete-wavelength intensity-modulated laser diodes. This modification enables the measurement of optical properties of materials at multiple wavelengths simultaneously. We further compare the performance of the FDM-SE to a commercial instrument by measuring the thickness of SiO2 films on a Si wafer, obtaining a difference between the measured thicknesses with both methods of less than 5 Å. The proposed FDM-SE technique therefore provides a more efficient alternative to conventional SE with a high accuracy for thickness measurements.

Adaptable and comprehensive approaches for long-read nanopore sequencing of polyadenylated and non-polyadenylated RNAs

The advent of long-read (LR) sequencing technologies has provided a direct opportunity to determine the structure of transcripts with potential for end-to-end sequencing of full-length RNAs. LR methods that have been described to date include commercial offerings from Oxford Nanopore Technologies (ONT) and Pacific Biosciences. These kits are based on selection of polyadenylated (polyA+) RNAs and/or oligo-dT priming of reverse transcription. Thus, these approaches do not allow comprehensive interrogation of the transcriptome due to their exclusion of non-polyadenylated (polyA-) RNAs. In addition, polyA + specificity also results in 3′-biased measurements of PolyA+ RNAs especially when the RNA input is partially degraded. To address these limitations of current LR protocols, we modified rRNA depletion protocols that have been used in short-read sequencing: one approach representing a ligation-based method and the other a template-switch cDNA synthesis-based method to append ONT-specific adaptor sequences and by removing any deliberate fragmentation/shearing of RNA/cDNA. Here, we present comparisons with poly+ RNA-specific versions of the two approaches including the ONT PCR-cDNA Barcoding kit. The rRNA depletion protocols displayed higher proportions (30%–50%) of intronic content compared to that of the polyA-specific protocols (5%–8%). In addition, the rRNA depletion protocols enabled ∼20–50% higher detection of expressed genes. Other metrics that were favourable to the rRNA depletion protocols include better coverage of long transcripts, and higher accuracy and reproducibility of expression measurements. Overall, these results indicate that the rRNA depletion-based protocols described here allow the comprehensive characterization of polyadenylated and non-polyadenylated RNAs. While the resulting reads are long enough to help decipher transcript structures, future endeavors are warranted to improve the proportion of individual reads representing end-to-end spanning of transcripts.

Selected Aspects of Positioning with the GNSS Galileo

The quality of Galileo system services is affected by the accuracy of distance determination from the user’s application to the individual satellite. The goal of our research was to find out what influence the accuracy of distance determination between the user’s application of the Galileo system and the cooperating satellites of the Galileo system has on the ability to determine the location of the user’s application. A solution based on Groebner’s algebraic approaches was used to determine the receiver user’s position. When creating distance measurement error models between the Galileo system user’s receiver and cooperating satellites, we assumed that the values of those errors considered all factors that affected the accuracy of those distance measurements. To evaluate the algorithms, we used a statistical set of 500 simulation results to determine the positioning of the user’s application of the Galileo system. If the distances between the user’s application and the individual satellite were measured accurately, then the user’s application coordinate errors had values between 1.86 × 10−9 m and −1.8 × 10−8 m. These errors should be equal to zero. The positioning error was caused by a numerical error in the calculation due to the software used. If the errors of distance determination from the user’s application to the individual satellite varied from −0.05 m to 0.09 m, then the error in determining the positioning of the user’s application of the Galileo system was from 0.0 m to 1.2 m. If the distances of the user’s receiver to the satellites were measured with errors greater than 0.09 m, the errors in determining its position were much larger. The simulation results confirmed the known fact that the satellites’ geometry influences the accuracy of determining the location of the user’s application. In the following research, we will solve the problem of how to reduce the sensitivity of the mentioned algorithms when determining the position of the satellite navigation system receiver due to errors in determining the distance from the user’s application to the individual satellite.

Modeling and application research of absolute gravimeter driven by a V-shaped linear ultrasonic motor.

A V-shaped linear ultrasonic motor (LUSM), used as a driving element for the absolute gravimeter, generates structural vibrations when the motor starts and stops, which interfere with and influence the accurate measurement of the absolute gravimeter. In order to address this problem and provide better stability and measurement accuracy, this paper designs a fuzzy proportional integral differential (PID) controller and realizes the drive control of the motor on a field programmable gate array (FPGA) using the Verilog hardware description language (HDL). The advantages of the proposed controller are verified by comparing the simulation results with those of the traditional PID controller. First, the technical index of the LUSM as the driving element is studied through theoretical analysis based on the operation mechanism of the absolute gravimeter. Then, the relationship between the output performance and the input parameters (excitation voltage, preload, and driving frequency) of the motor in a vacuum/natural environment is experimentally investigated. Finally, an experimental system is constructed, and experiments are conducted to measure the acceleration of gravity and compare with the test results of the habitual FG-5 absolute gravimeter. The experimental results show that the output performance of the V-shaped LUSM meets the requirements of the driving element of the absolute gravimeter. The combination of the two control methods can realize the repeatable and stable operation of the system. Moreover, the motor with a mass of only 92g can output force directly without transmission components. The complexity and the weight of the system are significantly reduced, which has certain advantages.

New impulse-based test method for early-age elastic modulus measurement in cementitious materials

Accurate monitoring of the elastic modulus evolution during the early-age fluid-solid transition in cementitious materials is crucial for understanding their mechanical behavior under early stresses. While existing methods, such as EMM-ARM, have proven effective, they are often associated with high costs or complex setups. This study presents the development of a low-cost, easy-to-implement system that employs impulse excitation applied to a composite beam, introducing the EMM-IRM method for the effective assessment of the elastic modulus of cement paste from the earliest stages of hydration. The use of impulse excitation is particularly advantageous in low-cost systems with accelerometers of lower sensitivity, as it enhances signal clarity and reduces interference from background noise, thereby improving measurement reliability. The system was validated through experimental comparisons with conventional EMM-ARM, cyclic compression, and traditional impulse excitation techniques, using Portland cement paste as the test material. The results show that EMM-IRM consistently estimates the elastic modulus, with a maximum deviation of 6.33% from other methods. Moreover, despite its cost-effectiveness, EMM-IRM demonstrates a higher signal-to-noise ratio compared to conventional EMM-ARM. This approach offers a practical solution for early-age characterization of cementitious materials, balancing cost, simplicity, and measurement accuracy.

Late intervention for type II endoleak is not determined by early sac diameter or volume changes after EVAR.

To compare the diagnostic accuracy and predictive value of aneurysm sac volume measurement versus maximum diameter measurement of abdominal aortic aneurysm sac after endovascular aneurysm repair (EVAR) in patients with type II endoleak. Retrospective study on a cohort of 103 patients who presented with a type II endoleak after EVAR for infrarenal abdominal aortic aneurysm. Maximum diameter and volumetric measurements were calculated on computed tomography follow-up scans at 3 months and 1 year after index surgery. Pearson correlation coefficient was used to determine linear association between diameter and volume; Mann-Whitney U test was used to compare patients with and without later intervention for type II endoleak with regard to diameter and volume change. The correlation between diameter and volume measurement was high (Rho: 0.890-0.980 with P < 0.0001). In 38 out of 103 patients (37%) with type II endoleak, a later intervention for endoleak management was performed; early diameter (P = 0.097), or volume (P = 0.387) change could not predict risk for later intervention. Both diameter and volume measurements can be used in the imaging follow-up of patients with endoleak type II after EVAR; however early changes in diameter or volume of the aneurysm sac cannot predict late intervention for type II endoleak.

Comparing the Accuracy and Efficiency of Leaf Gas Exchange Measurements of Excised and Nonexcised Strawberry (Fragaria ×ananassa Duch. ‘Camino Real’) Leaves

Acquiring leaf gas exchange (LGE) data from field experiments is critical for numerous research endeavors. However, because of the extended time needed to perform measurements and the necessity for moving equipment, the number of leaf samples collected is often limited. To address this concern, two studies were conducted to evaluate the accuracy and efficiency of LGE measurements of excised and nonexcised strawberry leaves. Research was conducted in experimental field plots located in Lubbock, TX, USA, where ‘Camino Real’ strawberry leaves was sampled for LGE measurements, during the 2021 growing season. Using an auto program mode, two LI-6400/XT portable machines simultaneously measured the LGE of nearby selected leaves from the same plant. Measurements were recorded every 30 seconds. After 90 seconds, the petiole of one leaf was cut (excised leaf treatment), and the auto program continued for an additional 480 seconds. The results indicated that although the LGE for nonexcised leaves remained stable, excised leaf LGE changed after excision. Within 30 seconds, the postexcision stomatal conductance to water vapor (gsw) and net leaf photosynthetic rate (A) exhibited nearly 97% and 99% accuracy, respectively, of nonexcised leaf gsw and A. However, the excised LGE decrease accelerated over time, with gsw continuing to decrease by more than 5% after 43 seconds, indicating ≤95% accuracy of the gsw results. The data suggested that strawberry LGE may be measured accurately within 30 to 40 seconds after leaf excision. During a separate experiment, the mean time to complete each individual strawberry LGE measurement was 68.4 seconds (±0.9 seconds) for nonexcised leaves. Conversely, the mean time to complete each LGE measurement of excised leaves was 42.2 seconds (±0.2 seconds). Therefore, leaf excision appears to be a viable method of maintaining accuracy and increasing the sample size while collecting strawberry LGE data.

A novel approach for the replacement of accuracy and precision measurements with the visual instrument agreement scale (VIAS) in evaluating the performance of four intraoral scanners and one shade measurement device

ObjectivesThe terms 'accuracy' and 'precision' are tightly defined in color science but are often used ambiguously in dental research. This study introduces the visual instrument agreement scale (VIAS), a new method for determining visual-instrumental agreement in dental colorimetry by comparing visually perceived and measured color differences. Materials and MethodsIn-vivo tooth color measurements were taken from 16 participants using four intraoral scanners (Primescan, Medit i700, Carestream CS3700, Trios 3) and one spectrophotometer (Vita Easyshade V). Visual shade assessment was also performed by one expert observer using the 3D Master shade guide. Statistical significance testing was conducted using the STRESS index to calculate VIAS, and the F-statistic was used to evaluate device performance. ResultsCarestream CS3700 achieved the highest visual-instrumental agreement with a VIAS score of 82%, performing significantly better than the other devices. Primescan, Medit i700, and Trios 3 showed scores of 76%, 75%, and 72%, respectively, with no significant differences between them. Vita Easyshade V scored 57%, performing significantly worse than the other devices. ConclusionsThe overall performance of the intraoral scanners was strong, with Carestream CS3700 approaching excellent performance. The VIAS method offers a practical, color science-based framework for evaluating visual-instrumental agreement and can be easily replicated using the freely available toolbox. Clinical SignificanceIntraoral scanners performed surprisingly better than a spectrophotometer specifically designed for tooth color measurement and which is often regarded as the gold standard. Additionally, VIAS offers a new, scientifically grounded approach for testing visual-instrumental agreement in dental colorimetry.

Electron probe microanalysis of trace sulfur in experimental basaltic glasses and silicate minerals

Abstract Sulfur (S) in the mantle is conventionally assumed to be exclusively stored in accessory sulfide phases, but recent work shows that the major silicate minerals that comprise &amp;gt;99% of the mantle could be capable of hosting trace amounts of S. Assessing the incorporation of trace S in nominally S-free mantle minerals and determining equilibrium S partitioning between these minerals and basaltic melt requires analyzing small experimental phases with low S contents. Here, we develop a protocol for EPMA analysis of the trace levels of S in silicate phases. We use a suite of natural and experimental basaltic glass primary and secondary standards with S contents ranging from 44 ppm to 1.5 wt%. The effects of beam current and counting time are assessed by applying currents ranging from 50 to 200 nA and total counting times between 200 and 300 s at 15 kV accelerating voltage. We find that the combination of 200 nA beam current with a 200 s counting time (80 s peak, 60 s each for upper and lower background, respectively) achieves precise yet cost-effective measurements of S down to a calculated detection limit of ~5 ppm and a blank-derived, effective detection limit of ~17 ppm. Close monitoring of the S peak intensity and position throughout the duration of each spot also shows that high currents and extended dwell times do not compromise the accuracy of measurements, and even low S contents of 44 ppm can be reproduced to within one standard deviation. Using our developed recipe, we analyzed a small suite of experimental clinopyroxenes (Cpx) and garnets (Gt) from assemblages of silicate partial melt + Cpx ± Gt ± sulfide, generated at 1.5 to 3.0 GPa and 1200 to 1300 °C. We find S contents of up to 71 ± 35 ppm in Cpx and 63 ± 28 ppm in Gt and calculate mineral-melt partition coefficients (Dsmin/melt) of up to 0.095 ± 0.064 and 0.110 ± 0.064 for DsCpx/melt and DsGt/melt, respectively. The sulfur capacity and mineral-partitioning for Cpx are in good agreement with SXRF measurements in a prior study by Callegaro et al. (2020), serving as an independent validation of our EPMA analytical protocol.

A Low-Cost Ultrasonic Sensor for Online Monitoring of Water Levels in Rivers and Channels

The measurement of flow parameters in rivers and channels is essential for anticipating floods, hydraulic modeling, and conducting water resource management studies. However, the high cost of existing equipment has resulted in a shortage of monitoring stations compared to actual requirements. This research focused on developing and validating a low-cost, highly accurate ultrasonic device that minimizes malfunctions for online monitoring of water levels in channels and streams. Considering the availability of components, cost, and the reported resolution of the product, the GY-Us42 sensor was selected for constructing the level gauge. The sensor operates within a range of 20 cm to 720 cm with a measurement accuracy of approximately 1 mm. The device integrates several error reduction mechanisms to enhance accuracy, including averaging multiple readings and temperature correction techniques. Laboratory data and field data gathered by both staff and shaft encoder were used for device validation. After constructing the main prototype and conducting various tests, multiple devices were installed in different locations within the Tehran rivers, and water depth data were collected over a specific period. Subsequently, data from other field sensors were also collected and used for device validation and accuracy assessment. The results indicate that the device's average error is below 3%, with a Root Mean Squared Error (RMSE) of 5.00 cm during field tests, demonstrates that the constructed device is an efficient tool for measuring water levels in streams, particularly during flood events.

Design and development of coastal marine water quality monitoring based on IoT in achieving implementation of SDGs

Indonesia, an archipelagic nation with about 70% ocean territory, relies on oceanographic data for efficient marine environment monitoring and natural resource sustainability. Current data collection is limited by tools measuring only single parameters and lengthy data collection times. This study proposes a marine coastal water quality monitoring tool based on the internet of things (IoT), capable of simultaneously measuring temperature, electrical conductivity, pH, and dissolved oxygen. Utilizing an Atmega328 and a battery lasting up to 119 hours, this system offers a cost-effective solution for real-time oceanographic data collection. Employing the ADDIE methodology, the results demonstrate high measurement accuracy compared to traditional methods, with accuracy of 90.5% for temperature, 93.50% for electrical conductivity, 93.67% for pH, and 96.82% for dissolved oxygen. The development of this tool aims to reduce costs and labor in capturing oceanographic data integrated with IoT, facilitate access and monitoring of water data, and make a significant contribution to achieving SDGs targets. The main focus on the goals of addressing climate change and life underwater, especially in the aspects of water resources management and protection of marine ecosystems in Indonesian.