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Knowledge regarding current flow rates through pipes and other components is crucial for most hydraulic systems. The hydraulic power can be computed in combination with the pressure, which may be used in many applications, such as predictive maintenance. Most flow rate sensors used in the field of fluid power operate invasively. Therefore, the measurement process itself alters the flow rate. Furthermore, most sensors operate accurately for stationary flow but produce inaccurate measurements for transient flow. A well‐known method of determining the flow rate is to measure the pressure difference between two points along a pipeline and calculate the flow rate based on the law of Hagen and Poiseuille. However, since the relation mentioned above only applies to laminar, steady, and incompressible flow, its usefulness for transient flows is limited. This paper derives a system equation based on the fundamental laws of fluid mechanics, which describe transient, incompressible pipe flow. As a result, the fundamental equations are solved in the Laplace domain and subsequently transformed back into the time domain. The four‐pole theorem relates the pressure difference and the volumetric flow rate. The analytical solution consists of a convolution integral containing a weighting function and the pressure difference. Compared to a simulation, the novel equation displays high accuracy for transient and stationary incompressible pipe flow. This equation paves the way for a soft sensor, which allows the noninvasive measurement of arbitrary volumetric flow rates within pipes. [ABSTRACT FROM AUTHOR]

Laser speckle contrast imaging (LSCI) is a non-invasive, powerful, and cost-effective imaging technique that has seen widespread adoption across various medical fields, particularly for blood flow imaging. While LSCI provides physicians with valuable insights into changes or occlusions in blood flow, the technique is susceptible to various factors and parameters that can impact measurement sensitivity and signal-to-noise ratio (SNR). These include the scattering of light, which can affect the quality and reliability of the LSCI data. The polarization of light holds significant promise to enhance the performance of LSCI. In this study, we employed polarization manipulation of light to investigate its impact on the performance of LSCI for measuring flow. Focusing on the application of LSCI in microcirculation within capillaries, we examined the effect of polarization control on the technique's flow measurement capabilities using a custom-designed phantom system. This phantom consisted of three tubes with inner diameters of 1.1 mm, 1.6 mm, and 2.8 mm, embedded in a polydimethylsiloxane (PDMS) matrix with optical properties similar to biological tissue. By manipulating the polarization of both the incident and reflected light, alternating between parallel and perpendicular states, we compared the performance of our LSCI system in detecting flow for different tube diameters and depths within the phantom. Our study revealed that while depth is a critical parameter influencing flow detection using LSCI, employing perpendicular polarization (between incident and reflected light) resulted in the lowest measurement error and highest SNR compared to parallel polarization and the absence of polarization control. [ABSTRACT FROM AUTHOR]

The mass flow rate of hydrogen leakage directly affects hydrogen diffusion and concentration distribution. In this paper, a test platform was constructed to measure mass flow rates during hydrogen leakage in the supply pipelines of the on-board hydrogen system. Hydrogen leakage tests were conducted under two different conditions. Mass flow rates were measured for tube fittings with various loosening angles and hydrogen supply pressures. The data were then fitted to extrapolate mass flow rates of hydrogen leakage beyond the tested conditions. Additionally, mass flow rates were measured for hydrogen supply pipelines with small holes of different shapes and sizes. The effects of pipeline size, hydrogen supply pressure, hole shape, and size on the hydrogen leakage mass flow rate were analyzed. Hydrogen leakage flow coefficients were corrected, and the accuracy of three calculation methods for hydrogen leakage flow was compared and analyzed based on the test results. The results provide a foundation for future numerical simulation models of hydrogen leakage diffusion. • A hydrogen leakage test platform for hydrogen supply pipeline has been set up. • Hydrogen flow rates of tube fittings with different loosening angles are measured. • Hydrogen flow rates of leakage holes with different shapes and sizes are measured. • Three flow calculation methods are comparatively analyzed based on test data. [ABSTRACT FROM AUTHOR]

We introduce a method for precise and accurate measurements of particle speeds in dense suspensions flowing at high rates and demonstrate the utility of the approach for revealing complex flow fluctuations during shearing in a setup that combines imaging with a confocal microscope and shearing with a rheometer. We scan the focal point in one dimension, aligned with direction of flow, producing absolute measurements of speed that are independent of suspension structure and particle shape. We compare this flow-direction line scanning approach with a complementary method we introduced previously, measuring speed using line scanning in the vorticity direction. By comparing results in various flow conditions, including shear-thinning and thickening regimes, we demonstrate the efficacy of our new approach. We find that both approaches exhibit qualitatively similar flow profiles, but a comparative analysis reveals a 15%–25% overestimation in speed measurement using vorticity line scanning, with discrepancies generated by anisotropic suspension microstructure under flow. Moreover, in the thickening regime where complex flow fields are present, both approaches capture local speed fluctuations. However, line scanning in the flow direction reveals and precisely captures stagnation and backflows, a capability not achievable with vorticity line scanning. The approach introduced here not only provides a refined technique for speed measurement in fast-flowing suspensions but also emphasizes the significance of accurate measurement techniques in advancing our understanding of flow behavior in dense suspensions, particularly in contexts where strong non-affine flows are prevalent. [ABSTRACT FROM AUTHOR]

This paper presents an approximate power flow model‐based forecasting‐aided state estimation estimator for power distribution networks subject to naive forecasting methods and nonlinear filtering processes. To this end, this estimator designs a voltage perturbation vector around the priori‐determined nominal value as the dynamic state variable, which enables more detailed depictions of voltage changes. Then, a state transition model incorporating nodal power variation is derived from the approximate power injection model. The constant state transition matrix working on power variations only consists of nodal impedance, which reduces the extensive parameter tuning effort when facing different estimation tasks. Furthermore, an approximate branch power flow observation equation is proposed to improve the filtering efficiency. The observation matrix with branch admittance information presents the linear filtering relationship between power flow measurements and forecasted states, omitting the complex iterative updates of the Jacobian matrix for nonlinear measurements. Finally, the overall estimated voltage state at each time sample is entirely obtained by combining the filtered voltage perturbation vector with the priori‐determined nominal value. Numerical simulation comparisons on a symmetric balanced 56‐node distribution system verify the performance of the proposed estimator in terms of accuracy and robustness under normal and abnormal conditions. [ABSTRACT FROM AUTHOR]

This paper discusses a full-fledged uncertainty analysis implementation using the Guide to the Expression of Uncertainty in Measurement (GUM) as framework. Currently, there are few examples of rigorous GUM implementations in hydrometry. This work fills this gap by demonstrating the use of the GUM framework to estimate the uncertainty of open-channel discharge measurements conducted with the velocity-area method using acoustic doppler velocimeters. The paper first presents the GUM protocol and the steps leading to discharge measurement followed by evaluations of Type A uncertainty from customized experiments, Type B uncertainty informed by prior experiments and engineering judgment, and the total discharge uncertainty. Finally, the uncertainty analysis (UA) implications and practical usage for data management and improvement of measurement processes are discussed. While the detail of the analysis can be further increased, the main role of this paper is to illustrate a step-by-step implementation of GUM procedures applied to natural-scale measurements using a GUM-compliant software. [ABSTRACT FROM AUTHOR]

For Francis turbines, speed-no-load (SNL) represents one of the most detrimental operating conditions, marked by significant pressure and strain fluctuations on the runner. Mitigating these fluctuations necessitates a comprehensive understanding and characterization of the flow phenomena responsible for their generation. This paper presents an experimental investigation of the flow at the inlet of a Francis turbine runner model operating in speed-no-load condition using high-speed stereoscopic and endoscopic particle image velocimetry (PIV). The measurements are made in a radial-azimuthal plane that covers the vaneless space and a large region in the interblade channel. This study marks the first-time measurement of critical flow phenomena at this operating point, performed in the runner. Instantaneous and average velocity fields are analyzed, along with other statistical data. The results not only confirm the stochastic nature of the flow at speed-no-load but also highlight the general structure of the flow observed in other studies. The high velocity fluctuations on the suction side are associated with a backflow extending into the vaneless space and a circulation zone occasionally generated by this backflow. Both phenomena are frequently present, but fluctuate stochastically. Additionally, two other circulation zones intermittently form on the pressure side of the blades. The presence of vortices, smaller than the circulation zones, near the blade's leading edge correlates with the backflow intensity. [ABSTRACT FROM AUTHOR]

Network flow measurement is an integral part of modern high-speed applications for network security and data-stream processing. However, processing at line rate while maintaining the required data structure within the on-chip memory of the hardware platform is a challenging task for measurement algorithms, especially when accuracy is of primary importance, such as in network security applications. Most of the existing measurement algorithms are no exception to such issues when deployed in high-speed networking environments and are also not tailored for efficient hardware implementation. Sketch-based measurement algorithms minimize the memory requirement and are suitable for high-speed networks but possess a low memory-accuracy trade-off and lack the versatility of individual flow mapping. To address these challenges, we present a hardware-friendly data structure named Sketch-based Pseudo-associative array Architecture (SPArch). SPArch is highly accurate and extremely memory-efficient, making it suitable for network flow measurement and security applications. The parallelism in SPArch ensures minimal and constant memory access cycles. Unlike other sketch architectures, SPArch provides the functionality of individual flow mapping similar to associative arrays, and the optimized version of SPArch allows the organization of counters in multiple buckets based on the flow sizes. An in-depth analysis of SPArch is carried out in this article and implemented SPArch on the Alveo data center accelerator card, demonstrating its suitability for high-speed networks. [ABSTRACT FROM AUTHOR]

A rectangular slit weir is used to measure small flows, namely, those flows less than 5 L/s and contraction ratios (b/B) less than 0.25. In the present study, flow tests were conducted in a laboratory setup with various contraction ratios (b/B) under models A (b/B = 1/12), B (b/B = 1/8), C (b/B = 1/6), D (b/B = 5/24), and E (b/B = 1/4). The dimensional analysis revealed that b/B, the height of the flow on the crest of the weir to the height of the weir crest (h/P), the Reynolds number (Re), and the Weber number (We) are effective parameters for predicting the discharge coefficient of the slit weir. The experimental results indicated that the discharge coefficient is variable for different contraction ratios; the maximum average discharge coefficient was achieved at the lowest b/B (Model A), with a value of 0.72. The minimum average discharge coefficient obtained in Model B equals 0.639. In addition, former prediction equations were compared with the obtained experimental data, and the minimum, average, and maximum errors were calculated. Furthermore, a relationship was established for deriving the discharge coefficient in slit weirs with R2 = 0.9212, RMSE = 0.02244, and MAE = 0.0134 based on the obtained experimental data with four effective parameters, b/B, h/P, Re, and We. [ABSTRACT FROM AUTHOR]

This research paper describes the development of a low-cost device for measuring wastewater flow rates in open channels, a significant advancement enabled by the evolution of microcomputers and processing techniques. A laboratory setup was constructed to validate the device's accuracy against a standard flow measurement method, optimizing key parameters to achieve a linear relationship between detected and set flow rates, while considering hardware limitations and energy efficiency. The central focus of the research was developing a method to measure the velocity of contaminated fluid using ultrasonic signals, employing the cross-correlation method for signal delay analysis in a stochastic environment. This was complemented by a procedure to measure fluid levels, also based on ultrasonic signals. The device's reliability was assessed through repeatability and uncertainty measurements, confirming its accuracy with an extended uncertainty not exceeding an average of 3.47% for flows above 40 L/min. The device has potential to provide valuable data on the operational dynamics of sanitary networks, crucial for developing and calibrating simulation models. [ABSTRACT FROM AUTHOR]

We study the instantaneous inference of an unbounded planar flow from sparse noisy pressure measurements. The true flow field comprises one or more regularized point vortices of various strength and size. We interpret the true flow's measurements with a vortex estimator, also consisting of regularized vortices, and attempt to infer the positions and strengths of this estimator assuming little prior knowledge. The problem often has several possible solutions, many due to a variety of symmetries. To deal with this ill posedness and to quantify the uncertainty, we develop the vortex estimator in a Bayesian setting. We use Markov-chain Monte Carlo and a Gaussian mixture model to sample and categorize the probable vortex states in the posterior distribution, tailoring the prior to avoid spurious solutions. Through experiments with one or more true vortices, we reveal many aspects of the vortex inference problem. With fewer sensors than states, the estimator infers a manifold of equally possible states. Using one more sensor than states ensures that no cases of rank deficiency arise. Uncertainty grows rapidly with distance when a vortex lies outside of the vicinity of the sensors. Vortex size cannot be reliably inferred, but the position and strength of a larger vortex can be estimated with a much smaller one. In estimates of multiple vortices their individual signs are discernible because of the nonlinear coupling in the pressure. When the true vortex state is inferred from an estimator of fewer vortices, the estimate approximately aggregates the true vortices where possible. [ABSTRACT FROM AUTHOR]

A multi-channel simultaneous emission non-invasive flow velocity measurement system is introduced and validated in this paper, which adapts to industrial large-diameter pipelines. In particular, the ultrasonic simultaneous emission mode is applied to the whole system to achieve real-time flow measurement. This technology reduces measurement errors in ultrasonic flow measurements caused by changes in fluid state and timing variations. Sixteen non-invasive ultrasonic transducers are used in the system, together with the precision measurement circuit, efficient data acquisition system and real-time display upper computer program. The flow rate can be accurately measured and displayed without interrupting the fluid flow. Furthermore, a period-invariant dual-threshold method is applied to locate feature points in the ultrasonic signals to ensure that high accuracy and stability are maintained in the final result. [ABSTRACT FROM AUTHOR]

To investigate the rolling wave characteristics of overland flow, this study calibrated the accuracy of the depth measurement system for shallow flow on slopes using acrylic sheets and optimized it as a dual-line laser water depth measurement system. Non-contact measurement methods were used to measure the water depth at the mature cross-section position of rolling waves in real time. This experiment designed a total of 5 measurement intervals, namely 0.04, 0.05, 0.10, 0.15, and 0.20 m. Three horizontal gradients were set for the slope, namely 3°, 9°, and 15°, and six horizontal gradients were set for the flow rate, namely 2, 4, 8, 12, 16, and 20 L/min. Each horizontal gradient was repeated for 5 experiments. The results indicated that the accuracy of the depth measurement system for shallow flow on slopes was confirmed to be 0.473 mm per grid, and the optimal spacing for the dual-line laser depth measurement system was 0.04 m. Both flow rate and slope significantly affected the wave speed, wave height, height difference, and frequency of rolling waves. The influence of flow rate (the effect size values were 0.655-0.963) was greater than that of slope (the effect size values were 0.232-0.874). The slope significantly affected the wavelength, while the flow rate did not significantly impact it. Wave speed increased with flow rate but the influence of flow rate on wave speed decreased with increasing slope. Under different slope conditions, wave height responded differently to flow rate. At a 3° slope, wave height initially increased and then decreased with increasing flow rate, whereas at higher slopes (9° and 15°), the wave height increased significantly under low flow conditions (2-8 L/min), with the increases of 3.74 and 4.63 mm, respectively. The difference in wave height between 3° and 9° slopes increased with flow rate, but the difference between 9° and 15° slopes decreased. The variation in height difference with slope was influenced by flow rate, showing a trend of initially increasing and then decreasing. Increased flow rates led to an increase in frequency, with the largest increase at a 15° slope, up to 2.37 Hz. The frequency differences between slopes decreased and then increased as flow rate increased, with a critical flow rate of 8 L/min. At a low slope (3°), wavelength fluctuated with flow rate, whereas at a high slope (15°), higher flow rates inhibited the development of wavelength. Under the high flow conditions (16-20 L/min), the wavelength differences between slopes were significant. This research provides a theoretical basis for improving the accuracy of slope overland flow measurements and further elucidating the dynamic characteristics of overland flow rolling waves. [ABSTRACT FROM AUTHOR]

In this study, the effects of the heat release rate (HRR) and horizontal vent area (HVA) on the fire phenomena of enclosure with upper horizontal vent (HV) and lower vertical vent (VV) were experimentally investigated. The HRR values of 0.16, 1.24, and 3.01 kW were tested, where HVAs were 1, 3, 6.25, 8, and 10 % of the floor area. The temperature profile inside the enclosure, thickness and temperature of the hot gas layer (HGL), and average velocity of the HV flow increased with an increase in HRR and a decrease in HVA. In contrast, the mass flow rate (MFR) of the HV flow increased with increases in HRR and HVA. Moreover, as the measurement points of the flow velocity on the HV were distant from the closest point to the VV, the HV flow velocity increased owing to the inclination of the fire plume caused by the inflow passing through the VV. The HGL temperature rise depended more on HRR than on HVA, whereas the MFR of the HV flow depended more on HVA than on HRR. The dependence of the average HV flow velocity on the HRR and HVA seemed to be comparable. Theoretical models for the velocity and MFR of the HV flow underpredicted the present experimental data, and the differences between them decreased with an increasing HRR. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Over the past decade, micro-liquid flow measurement has become increasingly important, particularly in India, where devices like syringe pumps, infusion pumps, and infusion device analyzers are critical in hospitals and research laboratories. These devices are essential for precise drug dosing in applications such as chemotherapy, pain management, insulin therapy, and other vital treatments, making accurate calibration crucial. To meet this need, the Fluid Flow Metrology Section at the CSIR-National Physical Laboratory (CSIR-NPL) in New Delhi has developed a state-of-the-art calibration facility for micro-liquid flow, capable of measuring flow rates from 10 mL/h to 1500 mL/h. The facility employs a static weighing method, utilizing a dual-range analytical balance with a capacity of 220 g/82 g and a digital timer as reference standards. This setup achieves an expanded uncertainty of 0.30% (at k=2) for both totalized volume and volume flow rate measurements, thereby ensuring the facility's status as a National Metrology Institute (NMI) in micro-liquid flow measurement. [ABSTRACT FROM AUTHOR]

Directed Energy Deposition (DED) processes necessitate a consistent material flow to the melt pool, typically achieved through pneumatic conveying of metal powder via thin pipes. This study aims to record and analyze the multiphase fluid–solid flow. An experimental setup utilizing a high-speed camera and specialized optics was constructed, and the flow through thin transparent pipes was recorded. The resulting information was analyzed and compared with coupled Computational Fluid Dynamics-Discrete Element Modeling (CFD-DEM) simulations, with special attention to the solids flow fluctuations. The proposed methodology shows a significant improvement in accuracy and reliability over existing approaches, particularly in capturing flow rate fluctuations and particle velocity distributions in small-scale systems. Moreover, it allows for accurately analyzing Particle Size Distribution (PSD) in the same setup. This paper details the experimental design, video analysis using particle tracking, and a novel method for deriving volumetric concentrations and flow rate from flat images. The findings confirm the accuracy of the CFD-DEM simulations and provide insights into the dynamics of pneumatic conveying and individual particle movement, with the potential to improve DED efficiency by reducing variability in material deposition rates. [ABSTRACT FROM AUTHOR]

Optical probes can be employed in dense and dilute fluidized beds. Their application is useful to determine particle volume fraction, bubble velocity, bubble size, and solid segregation in dense-phase fluidized-bed reactors, as well as particle-cluster velocity, size, and shape, in downer/riser units. The CREC-UWO team has developed a unique and miniaturized CREC Optiprobes System (CREC-GS-OPS) equipped with a GRIN (graded refraction index) lens. The GRIN lens creates a small volume of high light irradiation by focusing a laser a few millimetres away from the front of the probe tip. This design minimizes sensor intrusiveness and, as a result, provides trustworthy measurements of hydrodynamic parameters. Through the application of the CREC-GS-OPS, advances have been achieved, leading to (a) the development of a "Y-back" unit with graphite ferrules that protects the optiprobes from fibre-optic stresses and prevents the loss of sensor calibration and (b) the establishment of statistically-based data analysis. It is envisioned that through the introduction of a few design changes, the CREC Optiprobes will be made suitable for high-temperature applications. This will allow the measurement of catalyst flow recirculation (among other measurements), in industrial-scale fluidized-bed catalytic cracking units involving fluidized riser crackers and catalyst regenerators. [ABSTRACT FROM AUTHOR]

Particle image velocimetry and particle tracking velocimetry (PTV) have developed from two-dimensional two-component (2D2C) velocity vector measurements to 3D3C measurements. Rainbow particle tracking velocimetry is a low-cost 3D3C measurement technique adopting a single color camera. However, the vector acquisition rate is not so high. To increase the number of acquired vectors, this paper proposes a high probability and long-term tracking method. First, particles are tracked in a raw picture instead of in three-dimensional space. The tracking is aided by the color information. Second, a particle that temporarily cannot be tracked due to particle overlap is compensated for using the positional information at times before and after. The proposed method is demonstrated for flow under a rotating disk with different particle densities and velocities. The use of the proposed method improves the tracking rate, number of continuous tracking steps, and number of acquired velocity vectors. The method can be applied under the difficult conditions of high particle density (0.004 particles per pixel) and large particle movement (maximum of 60 pix). [ABSTRACT FROM AUTHOR]

Hydrographic observations and two-year current measurements revealed the flow around the Erimo Seamount between the Japan and Kuril trenches. Northward currents were observed to flow both around the seamount and on the eastern flank of the trench. Since the dissolved oxygen concentration of the former is higher than that of the latter, these currents correspond to the western and eastern branch currents of the deep western boundary current in the North Pacific, respectively. The western branch current forms a Taylor cap over the seamount, although during certain periods, it joins the eastern branch current. During such periods, a strong jet forms around the seamount and the Taylor cap is washed away. Such alternately intensified currents are consistent with previous observations of the Japan Trench. On the western flank of the trench, a southward current flows near the seafloor, while an eastward current is formed at a depth of 3360 m due to the confluence of the currents from north and south. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Water flow is an important piece of information in hydrological assessments, aiding in understanding variations in river flow and predicting its trends. Traditional contact-based methods for measuring water flow are greatly affected by environmental conditions during emergencies, with difficulties in installation and low measurement efficiency. To address this issue, this study explores a method for calculating video-based flow measurements using a non-contact spatio-temporal imaging approach. The study selects the Pukou section of the Chuhe River in Nanjing City as the experimental site for water flow detection. The detection method in this paper uses video flow measurement to measure the velocity of water flow. The collected data is processed visually and displayed on the interface of terminal equipment, and the collected data can be transmitted to a specified address in the format of the hydrological protocol. Experimental results indicate that using drones equipped with video flow measurement devices can rapidly and effectively complete water flow detection. The data can be displayed in a visual format on terminal equipment, facilitating viewing by relevant personnel. This form of detection is fast, safe, and environmentally adaptive, with the potential for practical applications. Further research into this detection method will promote the smart and integrated development of hydrological assessments. [ABSTRACT FROM AUTHOR]

In this review, we present the current status of phenomenological research on constraining the multi-dimensional proton (and nucleus) structure at high energies through studies of the so-called gluon Wigner distributions. We provide a brief pedagogical introduction into the corresponding theoretical definitions and modelling of exclusive and diffractive scattering observables in terms of the Wigner distribution. Also, we present a detailed outlook into the existing and planned experimental measurements that attempt to constrain the Wigner distribution. We briefly overview possible interconnections between various manifestations of the gluon Wigner distribution emerging, for instance, in azimuthal-angle correlations in (semi)exclusive reactions and elliptic flow measurements in inclusive processes. We also summarise the current knowledge on the most important processes that would potentially enable one to constrain the elliptic gluon density in the proton and to separate it from the genuine effect of hydrodynamic evolution in the flow measurements. [ABSTRACT FROM AUTHOR]

The microfluidic measurement of capillary flow can be used to evaluate the response of biological samples to stimulation, where distance and velocity are altered. Melt-extruded multi-bored microfluidic capillaries allow for high-throughput testing with low device cost, but simple devices may limit control over sample flow when compared to the more complex "lab-on-a-chip" devices produced using advanced microfluidic fabrication methods. Previously, we measured the dynamics of global haemostasis stimulated by thrombin by dipping straight vertical microcapillaries into blood, but only the most rapid response could be monitored, as flow slowed significantly within 30 s. Here, we show an innovative method to extend both the stimulation process and flow measurement time without increasing the cost of the device by adding simple loops to the flexible extruded device. The loops enable longer time-scale measurements by increasing resistance to flow, thereby reducing the dependence on high stimulus concentrations for rapid reactions. The instantaneous velocity and equilibrium heights of straight and looped vertical microcapillary films were assessed with water, plasma and whole blood, showing that the loops create additional frictional resistances, reduce flow velocity and prolong residence times for increased time scales of the stimulation process. A modified pressure balance model was used to capture flow dynamics with the added loop. Looped devices loaded with thrombin and collagen showed an improved detection of blood stimulation responses even with lower stimulus concentrations, compared to straight vertical capillaries. Thrombin-activated blood samples in straight capillaries provided a maximum measurement zone of only 4 mm, while the looped design significantly increased this to 11 mm for much longer time scale measurements. Our results suggest that extending stimulation times can be achieved without complex microfluidic fabrication methods, potentially improving concentration–response blood stimulation assays, and may enhance the accuracy and reliability. We conclude adding a loop to low-cost extruded microfluidic devices may bring microfluidic devices closer to delivering on their promise of widespread, decentralized low-cost evaluation of blood response to stimulation in both research and clinical settings. [ABSTRACT FROM AUTHOR]

Injecting hydrogen into natural gas pipelines for direct use by end users is an economical and effective method to realize long-distance transportation of hydrogen. However, the density of hydrogen is much lower than natural gas, and it tends to accumulate at the top of the pipeline, resulting in significant different flow characteristics of pure natural gas. Therefore, mixing hydrogen into natural gas pipelines will affect the accuracy of calorific value and flow rate measurement in the existing natural gas metering system. This article studies the flow characteristics of injecting hydrogen into natural gas using a T-shaped pipe and its impact on energy measurement through CFD numerical simulation. The results show that the energy metering equipment should be installed where the gas reaches a uniform mixture and the radial section velocity is centrally symmetrical. Injecting hydrogen with a lower position, and smaller main stream velocity will shorten the distance between the metering pipeline section and the mixing point, but a distance of at least 100 times the pipe diameter is still required. Thus, a mixing process combining a static mixer and flow straightener is proposed, which reduces this distance to within 40 times the pipe diameters. [Display omitted] • Composition and velocity changes in natural gas pipelines after hydrogen injection. • Define coefficient of variation velocity to quantify velocity central symmetry. • Static mixers have negative impact on HBNG flow measurement. • A high-efficient combined structure reduces the mixing distance from 100D to 40D. • Improve the existing measurement process to enable measurement of HBNG. [ABSTRACT FROM AUTHOR]

Filters with high throughput, minimal dead volume, and greater sensitivity to particle size are needed, which traditional benchtop filtration cannot provide. Leveraging microfabrication techniques developed by the electronics and optics industries, the filters presented here feature a unique serpentine "NanoRidge" structure, offering a continuous filtration gap spanning over three meters on a compact 4 × 14.5 mm2 footprint. This design provides more precise size filtration cut-offs and consistent flow paths compared to traditional membrane filtration systems. Despite challenges associated with glass substrate deformation impacting uniform filter gap sizes, the study provides valuable insights into the development of NanoRidge filters (NRFs) for enhancing filtration efficiency in preparatory techniques and sample analysis. This study describes the fabrication and testing of these new filter types and directly compares the performance to traditional membrane filters using the metrics of particle size cut-off (the smallest difference in particle size which can be filtered vs passed) and particle loss. The NanoRidge filters were characterized using imaging (during fabrication, post-fabrication and use, fluorescent particles captured and small molecule dye), pressure and flow measurements, and a series of particle sizes "filter or pass" studies. Particle capacity (100–250 nm) ranged from 5 × 108 to 7 × 109 in 1 ml samples at a flow rate of 100 μl/min with backpressure in the range of 1–3 Bar. The optimized fabrication procedure for the 150 nm NRF yielded a small particle recovery of 95% while also achieving a large particle filtration of 73%. High filtration efficiency was also proven in the final 60 and 80 nm NRF fabrication procedures at 96% and 91%, respectively. [ABSTRACT FROM AUTHOR]

Particle streak velocimetry (PSV) is a Lagrangian velocity measurement method based on streak imaging of moving particles and is regarded as the origin of particle image velocimetry (PIV) and particle tracking velocimetry (PTV). Recently, the PSV technique has undergone further developments, realizing measurements of three velocity components in three dimensions (3D3C), by combining with stereoscopic observation, defocused imaging, light field photography and /or holography. Moreover, image processing algorithms based on deep learning have been successfully applied to PSV. Compared with PIV and PTV, the PSV technique can exhibit several advantages, including extending the upper limit of the velocity measurement range under the same equipment conditions, measuring with lower illumination intensity, often an overall lower equipment complexity and cost for the same measuring requirement, as well as avoiding the particle matching problems of PTV. However, the PSV method also has obstacles to overcome, such as directional ambiguity and the difficulty in identifying streak crossings. For the directional ambiguity problem, there are currently time-coding, color-coding, brightness-coding and determination methods using additional image frames that can be employed. The main application areas of PSV currently include microfluidics, high-velocity flows and large-scale flow field measurements. This review presents the state of the art of PSV and summarizes advantages, disadvantages, accuracy, complexity and application of various configurations. The configurations discussed are focused on those measuring three velocity components and several examples are described in which PSV can be advantageously applied. The review concludes with some future developments that can be anticipated. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the present consensus paper was to provide recommendations for clinical practice on the individual etiological and modifying factors to be assessed in the individual diagnosis of caries, and the methods for their assessment, supporting personalized treatment decisions. Material and Methods: The executive councils of the European Organisation for Caries Research (ORCA) and the European Federation of Conservative Dentistry (EFCD) nominated ten experts each to join the expert panel. The steering committee formed three work groups which were asked to provide recommendations on (1) caries detection and diagnostic methods, (2) caries activity assessment, and (3) forming individualized caries diagnoses. The experts responsible for "individualised caries diagnosis" searched and evaluated the relevant literature, drafted this manuscript and made provisional consensus recommendations. These recommendations were discussed and refined during the structured process in the whole work group. Finally, the agreement for each recommendation was determined using an anonymous eDelphi survey. The threshold for approval of recommendations was determined at 70% agreement. Results: Ten recommendations were approved and agreed by the whole expert panel, covering medical history, caries experience, plaque, diet, fluoride, and saliva. While the level of evidence was low, the level of agreement was typically very high, except for one recommendation on salivary flow measurement, where 70% agreed. Conclusion: It is recommended that all aspects of caries lesion progression and activity, recent caries experience, medical conditions and medications, plaque, diet, fluoride and saliva should be synthesized to arrive at an individual diagnosis. Clinical Relevance: The expert panel merged evidence from existing guidelines and scientific literature with practical considerations and provided recommendations for their use in daily dental practice. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated the superior efficacy of bilateral internal thoracic artery (BITA) grafts compared to other graft methods in treating coronary artery disease. Competitive flow (CF) is a primary factor contributing to graft failure in the long term. For the first time, the CF of the BITA-Y graft has undergone rigorous numerical analysis. Through the application of transit time flow measurement (TTFM) and hemodynamic parameters, this study provides a new perspective on graft performance. Simulation results indicate that average flow, TTFM, and hemodynamic parameters fall within the critical range for stenosis severities below 90%. Specifically, at 80% stenosis, the mean graft flow (MGF) and pulsatility index (PI) of the left internal thoracic artery (LITA) were 0.071 cc/s and 27, respectively, while those of the right internal thoracic artery (RITA) were 0.211 cc/s and 11. With increasing stenosis severity, TTFM parameters remained within the clinical permissible limit (MGF > 0.34 cc/s and PI < 5). At 95% stenosis severity, the MGF and PI for LITA were 0.526 cc/s and 1.2, respectively, while those for RITA were 0.790 cc/s and 0.9. The results indicate the presence of competitive flow within the BITA-Y graft for stenosis severities below 90% area reduction, suggesting a potential risk of graft failure in the long term. Additionally, the results indicated that when there are significant differences in stenosis severity between the two native arteries, the BITA-Y graft is not optimal due to CF, characterized by low MGF and high reverse flow. [ABSTRACT FROM AUTHOR]

Understanding the flow physics behind fish schooling poses significant challenges due to the difficulties in directly measuring hydrodynamic performance and the three-dimensional, chaotic, and complex flow structures generated by collective moving organisms. Numerous previous simulations and experiments have utilized computational, mechanical, or robotic models to represent live fish. And existing studies of live fish schools have contributed significantly to dissecting the complexities of fish schooling. But the scarcity of combined approaches that include both computational and experimental studies, ideally of the same fish schools, has limited our ability to understand the physical factors that are involved in fish collective behavior. This underscores the necessity of developing new approaches to working directly with live fish schools. An integrated method that combines experiments on live fish schools with computational fluid dynamics (CFD) simulations represents an innovative method of studying the hydrodynamics of fish schooling. CFD techniques can deliver accurate performance measurements and high-fidelity flow characteristics for comprehensive analysis. Concurrently, experimental approaches can capture the precise locomotor kinematics of fish and offer additional flow information through particle image velocimetry (PIV) measurements, potentially enhancing the accuracy and efficiency of CFD studies via advanced data assimilation techniques. The flow patterns observed in PIV experiments with fish schools and the complex hydrodynamic interactions revealed by integrated analyses highlight the complexity of fish schooling, prompting a reevaluation of the classic Weihs model of school dynamics. The synergy between CFD models and experimental data grants us comprehensive insights into the flow dynamics of fish schools, facilitating the evaluation of their functional significance and enabling comparative studies of schooling behavior. In addition, we consider the challenges in developing integrated analytical methods and suggest promising directions for future research. [ABSTRACT FROM AUTHOR]

Atmospheric carbonyl sulfide (COS) has received increasing attention as a potential tracer for investigating the global carbon cycle. Owing to the irreversible photosynthetic absorption of COS, changes in the atmospheric COS mole fraction can be related to terrestrial gross primary production. However, the instability of COS in high-pressure cylinders has hampered the accurate determination of atmospheric COS. Here, we report a dynamic dilution method for generating reference gas mixtures containing COS at ambient levels (ca. 500 pmol mol -1). Our method combined a dynamic dilution system employing a high-accuracy mass flow measurement system and a dry reference gas mixture prepared gravimetrically as a parent gas mixture containing a micromole-per-mole level of COS filled in a high-pressure aluminium cylinder. The storage stability of COS at this level was experimentally validated for three gravimetrically prepared dry reference gases over a period of more than 1 decade. We evaluated the dilution performance of the developed method using a gravimetric parent gas mixture containing approximately 1 µ mol mol -1 of COS and chlorodifluoromethane (HCFC-22). Excellent repeatability (0.2 % for COS and 0.4 % for HCFC-22 in terms of relative standard deviation; RSD), reproducibility (COS: 0.1 %; HCFC-22: 0.3 %), and dilution linearity (R2>0.99 for both COS and HCFC-22) were obtained and were corroborated by the nearly constant ratio of the normalized gas chromatography–mass spectrometry (GC/MS) response of COS to HCFC-22. The dilution accuracy was examined by comparing the determined HCFC-22 mole fractions in a dynamically diluted parent gas mixture from a mass flow rate measurement system and GC/MS calibrated using a gravimetrically diluted parent gas mixture. The mole fractions of HCFC-22 from these two methods agreed within an acceptable difference of approximately 2 pmol mol -1 , validating the dilution accuracy of the developed method. By re-evaluating the experimental data, we determined the mole fractions of COS and HCFC-22 in an ambient-air-based reference gas mixture, with relative standard deviations of 0.1 % for COS and 0.3 % for HCFC-22. These results demonstrated that the developed method can accurately generate reference gas mixtures containing COS at ambient levels, which we expect will support long-term observations of atmospheric COS. [ABSTRACT FROM AUTHOR]

Myocardial revascularization has been known to not affect the prognosis in some patients. Coronary artery bypass graft (CABG) failure may develop one year after CABG surgery. This is accompanied by a high risk of developing myocardial infarction after complete myocardial revascularization in obstructive coronary artery disease (CAD) due to microvascular dysfunction. The study of microvascular dysfunction using intraoperative stress tests with adenosine triphosphate (ATP) allows for the assessment of the coronary bypass flow reserve (CBFR) and the risk of graft failure one year after surgery. The study included 79 CAD patients (238 grafts) who underwent dynamic single-photon emission computed tomography (SPECT) before CABG and dynamic transit time flow measurement (TTFM) during CABG at rest and at stress. The CBFR was calculated by the ratio of the mean graft flow (MGF) at stress to the MGF at rest. A multivariate regression model showed that the MGF at rest (p = 0.043), the MGF at stress (p = 0.026) and the CBFR (p = 0.0001) were significant independent predictors of graft failure. As a result of ROC analysis, the threshold CBFR < 1.67 units correlated with graft failure more closely (sensitivity 82%, specificity 90%) The CBFR is a significant independent predictor of graft failure for up to 16 months. [ABSTRACT FROM AUTHOR]

Emulsification processes are often found in the process industry and their evaluation is crucial for product quality and safety. Numerous methods exist to analyze critical quality attributes (CQA) such as the droplet sizes and droplet size distribution (DSD) of an emulsification process. During the emulsification process, the optical process accessibility may be limited due to high disperse phase content of liquid-liquid systems. To overcome this challenge, a modular, optical measurement flow cell is presented to widen the application window of optical methods in emulsification processes. In this contribution, the channel geometry is subject of optimization to modify the flow characteristics and produce high optical quality. In terms of rapid prototyping, an iterative optimization procedure via SLA-3D printing was used to increase operability. The results demonstrated that the flow cell resulting from the optimization procedure provides a broad observation window for droplet detection. [ABSTRACT FROM AUTHOR]

This experimental study focused on the measurement and analysis of the impact force caused by a tsunami bore on a coastal structure. The bore wave was produced by a dam break mechanism. The water depth in the reservoir and the location of the coastal structures were varied to simulate different impact scenarios. The time history of the force resulting from the impact of the bore wave on the coastal structure was measured. The propagation of the bore wave along the flume was recorded and the video recordings were converted into digital data using an image-processing technique in order to determine the flow depth variations with time. The hydrostatic forces and the corresponding depth and time-averaged hydrodynamic forces as well as the maximum hydrodynamic forces were acquired for each scenario. The ratio of hydrodynamic to hydrostatic forces were obtained, and it was observed that the calculated averaged ratio was within the recommended design ratio. The results indicate that an increase in the reservoir level caused an increase in the magnitude and intensity of the impact forces, however, the relationship was non-linear. Moreover, it was found that the location of the structure did not play a significant role on the intensity of the impact forces. [ABSTRACT FROM AUTHOR]

Purpose: To present and assess an outlier mitigation method that makes free‐running volumetric cardiovascular MRI (CMR) more robust to motion. Methods: The proposed method, called compressive recovery with outlier rejection (CORe), models outliers in the measured data as an additive auxiliary variable. We enforce MR physics‐guided group sparsity on the auxiliary variable, and jointly estimate it along with the image using an iterative algorithm. For evaluation, CORe is first compared to traditional compressed sensing (CS), robust regression (RR), and an existing outlier rejection method using two simulation studies. Then, CORe is compared to CS using seven three‐dimensional (3D) cine, 12 rest four‐dimensional (4D) flow, and eight stress 4D flow imaging datasets. Results: Our simulation studies show that CORe outperforms CS, RR, and the existing outlier rejection method in terms of normalized mean square error and structural similarity index across 55 different realizations. The expert reader evaluation of 3D cine images demonstrates that CORe is more effective in suppressing artifacts while maintaining or improving image sharpness. Finally, 4D flow images show that CORe yields more reliable and consistent flow measurements, especially in the presence of involuntary subject motion or exercise stress. Conclusion: An outlier rejection method is presented and tested using simulated and measured data. This method can help suppress motion artifacts in a wide range of free‐running CMR applications. [ABSTRACT FROM AUTHOR]

Sweeping jet actuator (SJA) has been widely applied for active flow control in open flows. In this paper, the SJA character in compressor cascade and its performance for separation control in inner flows are discussed. Time-averaged and transient flow field measurement, together with visualization methods are utilized. It is found that endwall effects are important for both SJA behaviors and SJA performance for separation control in compressor cascades. There is a maximum of 12.7% total pressure loss reduction with SJA placed near the separation position, close to the endwall and under appropriate flowrate. The characteristic frequencies in the flow field contribute to the capture of influence regions of vortices and excitation jets. Two concentrated shedding vortices and SJA jets impact region helped to judge that SJA energizes low momentum fluids in a large region and matches the high loss core well. To be concrete, the flow separation control mechanism of SJA lies on the interruption of the blade suction surface boundary layer development and the restriction of the lifting of the boundary layer from end- wall towards blade suction surface. [ABSTRACT FROM AUTHOR]

Flexible pressure sensors are lightweight and highly sensitive, making them suitable for use in small portable devices to achieve precise measurements of tiny forces. This article introduces a low-cost and easy-fabrication strategy for piezoresistive flexible pressure sensors. By embedding silver nanowires into a polydimethylsiloxane layer with micro-pyramids on its surface, a flexible pressure sensor is created that can detect low pressure (17.3 Pa) with fast response (<20 ms) and high sensitivity (69.6 mA kPa−1). Furthermore, the pressure sensor exhibits a sensitive and stable response to a small amount of water flowing on its surface. On this basis, the flexible pressure sensor is innovatively combined with a micro-rotor to fabricate a novel urinary flow-rate meter (uroflowmeter), and results from a simulated human urination experiment show that the uroflowmeter accurately captured all the essential shape characteristics that were present in the pump-simulated urination curves. Looking ahead, this research provides a new reference for using flexible pressure sensors in urinary flow-rate monitoring. ARTICLE HIGHLIGHTS: • A flexible pressure sensor is presented based on a micro-pyramid array and silver nanowires and with low detection limit, high sensitivity, and fast response. • The sensor responds accurately and stably to human pulse signals and rapidly changing cyclic loads. • The sensor can accurately and sensitively detect dynamic water flow passing over its upper surface, and the uroflowmeter designed using it has considerably high detection accuracy. [ABSTRACT FROM AUTHOR]

The radial distribution of material feeding onto a screen surface is an important factor affecting vibration screening performance, and it is also the main basis for the optimization of the operating parameters of a vibration screening system. In this paper, based on near-infrared properties, a real-time measurement method for the mass flow rate of grain vibration feeding was proposed. A laser emitter and a silicon photocell were used as the measuring components, and the corresponding signal processing circuit mainly composed of a T-type I/V convertor, a voltage follower, a low-pass filter, and a setting circuit in series was designed. Calibration test results showed that the relationship between grain mass flow rate and output voltage could be described using the Gaussian regression model, and the coefficient of determination was greater than 0.98. According to the working principle of the grain cleaning system of combine harvesters, the dynamic characteristics of grain vibration feeding were analyzed using discrete element method (DEM) simulations, and the monitoring range of the sensor was determined. Finally, grain mass flow rate measurement tests were carried out on a vibration feeding test rig. The results indicated that the grain mass measurement error could be controlled within 5.0% with the average grain mass flow rate in the range of 3.0–5.0 g/mm·s. The proposed measurement method has potential application value in the uniform feeding control systems of vibration feeders. [ABSTRACT FROM AUTHOR]

Several means are used for flow measurement, including the flumes that are of interest to the present study. The operating principle of the flume is based on the lateral contraction of the walls of a trapezoidal channel that ends in a triangular section extended by a throat of the same section. The convergent part of the flume accelerates the flow from a subcritical state to a critical state in the throat where a control section is created. Thus, the flow can be determined by taking a single depth reading in the inlet cross-section of the flume. The recommended device is simple and compact in shape, requiring a minimum of space compared to known trapezoidal flumes. Furthermore, the device has been designed to be used in open channels regardless of the shape. Therefore, the flume has the property of being of a universal range. A rigorous theoretical development led to the derivation of the governing discharge coefficient Cd relationship, solely depending on the dimensionless parameter M1 = mh1/b1, where m is the side slope of the flume, h1 is the upstream flow depth, and b1 is the inlet cross-section width of the converging part of the flume. Based on 1023 pairs of values Q-h1 collected from twelve tested flumes of different practical dimensions, the in-depth analysis of laboratory observations corroborated the validity and reliability of the theoretical relationship governing Cd within the wide range 0.10 ≤ M1 ≤ 0.95, since the maximum deviation is only 0.215% when compared to observations. Among the twelve tested devices, only the results of the observations carried out on one device will be presented herein. The observations collected on this device are considered the most unfavourable compared with those carried out on the eleven other tested devices, especially regarding the deviation affecting the discharge coefficient Cd. [ABSTRACT FROM AUTHOR]

Abstract Laser speckle contrast imaging (LSCI) is a non-invasive, powerful, and cost-effective imaging technique that has seen widespread adoption across various medical fields, particularly for blood flow imaging. While LSCI provides physicians with valuable insights into changes or occlusions in blood flow, the technique is susceptible to various factors and parameters that can impact measurement sensitivity and signal-to-noise ratio (SNR). These include the scattering of light, which can affect the quality and reliability of the LSCI data. The polarization of light holds significant promise to enhance the performance of LSCI. In this study, we employed polarization manipulation of light to investigate its impact on the performance of LSCI for measuring flow. Focusing on the application of LSCI in microcirculation within capillaries, we examined the effect of polarization control on the technique's flow measurement capabilities using a custom-designed phantom system. This phantom consisted of three tubes with inner diameters of 1.1 mm, 1.6 mm, and 2.8 mm, embedded in a polydimethylsiloxane (PDMS) matrix with optical properties similar to biological tissue. By manipulating the polarization of both the incident and reflected light, alternating between parallel and perpendicular states, we compared the performance of our LSCI system in detecting flow for different tube diameters and depths within the phantom. Our study revealed that while depth is a critical parameter influencing flow detection using LSCI, employing perpendicular polarization (between incident and reflected light) resulted in the lowest measurement error and highest SNR compared to parallel polarization and the absence of polarization control.

A spillway comprises several sections, primarily the crest and chute, essential for safe water flow from an upstream reservoir to a downstream river. Incorporating a hydrofoil crest and stepped chute features creates an efficient Hydrofoil-Crested Stepped Spillway (HCSS). The hydraulic features of the 60 HCSS models, which were designed through the National Advisory Committee for Aeronautics (NACA) equation, are assessed through laboratory experiments under a skimming flow regime, where the five hydrofoil formation indexes (t), three numbers of steps (Ns), and four chute angles (θ) are of concern. The findings indicate that an escalation in the ratio of upstream depth (yup) to spillway height (P), correlates with a rise in the discharge coefficient (Cd) in HCSSs. Furthermore, augmenting the t effectively boosts the Cd value. On average, the Cd value of the crest at t = 1 surpasses that at t = 0.2 by 20 %. This increase in t accentuates the curvature of the spillway crest, thereby enhancing the curvature of streamlines and reducing the flow distance therein. The Energy Dissipation Ratio (EDR) of HCSS is influenced by factors such as t (positively correlated), Ns (positively correlated), and θ (negatively correlated). Optimal performance of the HCSS is observed at t = 1, where both the Cd and EDR reach their peak values.

Abstract To address the measurement accuracy challenges posed by the internal flow complexity in atypical circular bend pipes with short turning sections and without extended straight pipe segments, this study designed an experimental circular “S”-shaped bent pipe with a diameter of 0.4 m and a bending angle of 135°. Numerical analysis was used to determine the stable region for velocity distribution within the experimental segment. Furthermore, a novel evaluation method based on the coefficient of variation was proposed to accurately locate the optimal position for installing thermal mass flow meters on the test cross section. Additionally, a formula for calculating the pipeline flow rate based on velocity differences was derived. This formula considers pipeline flow as the dependent variable and uses the velocity at two points in the test cross section as the independent variable. Experimental validation on a primary standard test bench demonstrated that the flow rate calculated by this method had an error controlled within 0.625% compared to the standard flow rate, thus effectively verifying the method’s high accuracy and engineering applicability. This research provides a new testing methodology and practical basis for flow measurement in complex pipeline systems, offering significant guidance for research and applications in related fields.

The effects of pressure drop across cardiac valve cushion regions and endocardial wall strain in the early developmental stages of a teleost species heart are poorly understood. In the presented work, we utilize microscale particle image velocimetry (μPIV) flow measurements of developing medaka hearts from 3 to 14 dpf (n = 5 at each dpf) to quantify the pressure field and endocardial wall strain. Peak pressure drop at the atrioventricular canal (ΔPAVC) and outflow tract (ΔPOFT) show a steady increase with fish age progression. Pressure drops when non-dimensionalized with blood viscosity and heart rate at each dpf are comparable with measurements in zebrafish hearts. Retrograde flows captured at these regions display a negative pressure drop. A novel metric, Endocardial Work (EW), is introduced by analyzing the ΔPAVC-strain curves, which is a non-invasive measure of work required for ventricle filling. EW is a metric that can differentiate between the linear heart stage (< 100 Pa-%), cardiac looped chamber stage (< 300 Pa-%), and the fully formed chamber stage (> 300 Pa-%). [ABSTRACT FROM AUTHOR]

Streamflow records are biased toward large streams and rivers, yet small headwater streams are often the focus of ecological research in response to climate change. Conventional flow measurement instruments such as acoustic Doppler velocimeters (ADVs) do not perform well during low‐flow conditions in small streams, truncating the development of rating curves during critical baseflow conditions dominated by groundwater inflow. We revisited an instantaneous solute tracer injection method as an alternative to ADVs based on paired measurements to compare their precision, efficiency, and feasibility within headwater streams across a range of flow conditions. We show that the precision of discharge measurements using salt dilution by slug injection and ADV methods were comparable overall, but salt dilution was more precise during the lowest flows and required less time to implement. Often, headwater streams were at or below the depth threshold where ADV measurements could even be attempted and transects were complicated by coarse bed material and cobbles. We discuss the methodological benefits and limitations of salt dilution by slug injection and conclude that the method could facilitate a proliferation of streamflow observation across headwater stream networks that are highly undersampled compared to larger streams. [ABSTRACT FROM AUTHOR]

This study introduces analyzes a slow-growing degradation effect that can occur when using thin catalyst-coated membranes for PEM water electrolysis. The electric current through a test cell increased during experiments in potentiostatic operation, but the oxygen evolution rate contradicted Faraday's law. Impedance measurements below the decomposition voltage of water at the beginning and end of the experiment revealed that a new electrical phase boundary (semicircle in the Gaussian plane) arose. This allows electrons to flow across this phase boundary without triggering electrochemical reactions. SEM/EDX cross-sectional analyses show the formation of globular iridium clusters within the membrane, which grow from the anode through the membrane to the cathode. These clusters, whose formation is not yet understood, are most likely responsible for the formation of slowly-increasing short circuits between the electrodes. • Globular iridium cluster can grow from anode to cathode of a PEM-CCM and connect them. • Measuring the oxygen production rate is a useful tool to indicate the slow growth of short circuits during operation. • Impedance measurements below the decomposition voltage of water can provide important information about short circuits. [ABSTRACT FROM AUTHOR]

The usage of liquefied hydrogen (LH 2) is growing fast as the EU aims to be climate-neutral by 2050. Therefore, reliable and consistent measurements of LH 2 amounts (as determined by flow meters) will become increasingly important for custody transfers. Reliability and consistency of measurements is established from calibration. Due to the lack of facilities being able to calibrate flow meters directly with LH 2 as calibration fluid, the question arises whether the measurement error of the calibration performed on a different fluid and different process conditions are representative for the errors when measuring LH 2. An on-site calibration of two turbine meters measuring LH 2 flow was performed. A Coriolis mass flow meter calibrated on water was used as a reference in conjunction with a dedicated flow meter model, which was validated by a directly SI-traceable calibration on liquefied natural gas. LH 2 flow rates were within 1000 kg/h and 3000 kg/h, which are relevant to hydrogen transport by LH 2 trailers. The analysis of the measurement data reveal errors on totalized mass ranging from 2.0 % to 2.9 % with a total calibration uncertainty of 1.3 % (k = 2), where the main uncertainty source was identified as the on-site density estimate necessary to convert the volume flow measurements into mass flow measurements. The results indicate the need for reliable and accurate temperature measurements (the latter allowing for an accurate density estimate), so that volume based and mass based amount measurements can be compared with smaller uncertainties. • Reliable measurements of liquefied hydrogen amounts will be crucial for custody transfer. • Direct calibration of flow meters on liquefied hydrogen is currently not possible. • Novel results of liquefied hydrogen flow measurement of an on-site calibration are presented. • The analysis reveals errors between 2.0 % and 2.9 % with an uncertainty of 1.3 % (coverage factor = 2). • The main uncertainty source was identified as the on-site density estimate. [ABSTRACT FROM AUTHOR]