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This study establishes an ultrasonic open channel flow measurement test and numerical simulation model and systematically compares the performance and reliability of the ultrasonic method and the traditional flowmeter in flow measurement in the irrigation area by observing and analysing the test data and combining it with the numerical simulation. In the indoor ultrasonic flowmeter flow measurement experiments in the trapezoidal nullah section, the flow rate measurement was carried out by using a high-precision variable slope flume and a variety of flow measurement tools. A numerical study was carried out using the VOF method to calculate the flow in the open channel flume under two-phase flow conditions. Combining experimental measurements and numerical simulations, this study aims to quantify the magnitude of flow measurement errors and water surface fluctuations in open channel flumes and to address the discrepancies between different flow measurement methods in open channels in irrigation areas.

As the current guidelines on myocardial revascularization recommend, transit-time flow measurement (TTFM) is increasingly used for intraoperative graft flow analysis during coronary artery bypass grafting (CABG) as a less invasive, more highly reproducible, and less time-consuming method. In addition to the morphological assessment using color Doppler, mean graft flow (Qm) > 15 ml/min, pulsatility index (PI) < 5.0, diastolic filling (DF) > 50%, and systolic reverse flow (SRF) < 4% have been reported to predict patent CABG grafts. However, it is difficult to determine the clear-cut cut-off value of these parameters, because they varies with the hemodynamic characters, including fractional flow reserve (FFR) of the target coronary artery. In addition to these parameters, we focused on fast Fourier transform (FFT) analysis, because the TTFM waveform morphology may be more important than Qm itself. FFT analysis is based on the principle that any periodic waveforms can be broken down into a series of pure sine waves or harmonics. Herein we review FFT analysis of the intraoperative TTFM waveforms for quality assessment of CABG grafts.

Degradation of fast response pressure-sensitive paints (PSP) above room temperature is a serious problem for PSP measurements in high-temperature environments. A standard polymer-ceramic PSP (PC-PSP) composed of platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin (PtTFPP), titania particles and poly(isobutyl methacrylate) (polyIBM) was characterized to elucidate the degradation mechanism. Applying a two-gate lifetime-based method, the PC-PSP has sufficient pressure and temperature sensitivities even at 100 °C, while the luminescence intensity significantly decreases during the test. Subsequent measurements on thermal and photostability as well as luminescence spectra reveal that the main cause of the degradation is the photodegradation of PtTFPP due to direct exposure of the dye molecules to the atmosphere. In order to suppress such degradation, a small amount of urethane resin is added to the dye solution as a simple additional step in the preparation of PC-PSP. The addition of the urethane resin significantly reduces the degradation of the PSP, although its time response is slightly slower than that of the standard PC-PSP.

Accurate water metering is essential for effective water management, especially for measured and equitable distribution of canal flows, most imperative in Pakistan. The inflows distributed through outlets must adhere to pre-designated levels, defined by Punjab Irrigation Department from head to tail. With recent channels lining, the outlets sanctioned flow are found changed requiring adjustments. Furthermore, there is lack of reliable mechanisms for continuous flow regulations, resulting in unmanaged distributions. The focus of the reported work was on precise and real-time discharge monitoring at outlets using a newly developed device utilizing Artificial Intelligence. During validation training, strong agreement was observed, and all evaluation parameters supported the device accuracy for measurements. In detailed studies of canal operations, the sanctioned discharges of individual outlets along selected distributaries were found significantly inequitable. Out of 162 outlets, 42 were suspended for being unmanaged, with tail users receiving ≤ 50% of their fair intakes. Additionally, there were instances of massive irrational supplies exceeding 200% of allocated discharges. The developed device has potential to accurately measure real-time discharges for managed distributions. Conclusively, the challenging task of fair and equity-based discharge allocations, in conjunction with Warabandi system, necessitates the reevaluation of the allocated flow quantity at each outlet.

A commercial micropump should provide properties that justify the simple structure and miniaturization, high reliability, simple working principle, low cost and no need for complex controller. In this study, two novel piezoelectric actuated (lead zirconate titanate-PZT) valveless micropumps that can achieve high flow rates by pumping chambers and fixed reservoirs were designed and fabricated. Extensive experiments were conducted to investigate the effects of hydrodynamic and electromechanical on flow rates of the Single Diaphragm Micropump (SDM) and the Bi-diaphragm Micropump (BDM). BDM had two actuators facing to the same chamber at 180-degree phase shift. The primary features of the proposed designs were the high flow rates at low driving voltages and frequencies with the help of innovative design geometry. 3D-printing technique providing one-step fabrication for integrated micropumps with fixed reservoir was used. The micropump materials were biocompatible and can be used repeatedly to reduce costs. Mechanical parameters such as tensile test for silicon diaphragm, surface topography scanning by microscopy techniques and drop shape analysis for hydrophobic property were investigated to reveal surface wetting and flow stability. In addition, the effect of reservoir height was investigated and the calibration flow rates were measured during the inactive periods. The maximum diaphragm displacements were obtained at 45 V and 5 Hz. The maximum flow rate of SDM and BDM at 45 V and 20 Hz were 32.85 ml/min and 35.4 ml/min respectively. At all driving voltage and frequency levels, BDM had higher flow rates than of SDM.

Background Competitive flow (CF) in coronary artery bypass grafting (CABG) occurs when graft flow is impaired due to higher competing flow from either the native circulation or another graft and may result in functional graft occlusion. We report a case of functional graft occlusion of a left internal mammary artery (LIMA) due to flow competition with a saphenous vein graft (SVG) and discuss the rationale of ligating the graft responsible for the CF. Case presentation The case refers to a 56-year-old man with an isolated subtotal ostial left anterior descending (LAD) lesion who underwent conventional double on-pump CABG with an in situ (LIMA) to the LAD and a centrally anastomosed SVG to the Diagonal branch (D1). Concerning the initial Transit-time flow measurements (TTFM), the SVG had a mean graft flow (MGF) of 49 ml/min, a Pulsatility index (PI) of 1 and a Diastolic flow (DF) of 66%. The LIMA graft had an MGF of 31 ml/minute, a PI of 3.8, a DF of 80%, but a Backward flow (BF) of 8%. As the LIMA BF was quite high, we suspected competitive flow of the graft and thus decided to transiently apply a bulldog clamp to the SVG, to check if the LIMA TTFM would change. Indeed, MGF was 44 ml/minute, the PI was 2.3, DF was 60%, and BF was 0.9%. Despite these results, the operating surgeon did not alter the revascularization plan and the operation was finished. The patient was discharged uneventfully. However, in a 6-month follow-up, the patient was symptomatic and with poor ejection fraction, and the diagnostic work-up revealed the functional occlusion of the LIMA graft with a string sign, and a patent SVG. After Heart Team consultation and patient update, he underwent left main stent implantation. Conclusions There should be a great degree of suspicion for CF with high BF values, even when the rest of the parameters measured during TTFM are normal or marginal. Also, the location of the LAD stenosis proximal to the D1 is a risk factor for CF when both arteries are grafted. Changing the revascularization plan based on TTFM is warranted for optimal outcomes.

A new measurement device, consisting of swirling blades and capsule-shaped throttling elements, is proposed in this study to eliminate typical measurement errors caused by complex flow patterns in gas-liquid flow. The swirling blades are used to transform the complex flow pattern into a forced annular flow. Drawing on the research of existing blockage flow meters and also exploiting the single-phase flow measurement theory, a formula is introduced to measure the phase-separated flow of gas and liquid. The formula requires the pressure ratio, Lockhart-Martinelli number (L-M number), and the gas phase Froude number. The unknown parameters appearing in the formula are fitted through numerical simulation using computational fluid dynamics (CFD), which involves a comprehensive analysis of the flow field inside the device from multiple perspectives, and takes into account the influence of pressure fluctuations. Finally, the measurement model is validated through an experimental error analysis. The results demonstrate that the measurement error can be maintained within ±8% for various flow patterns, including stratified flow, bubble flow, and wave flow.

Large-scale groundwater flow modelling demands comprehensive geological investigation (GI) to accurately predict groundwater dynamics during open-cut and underground mining. Due to the existence of large-scale heterogeneity (e.g., fault and fracture) in natural geological strata (e.g., overburden soil, rock mass and coal seam), the in-situ flow measurement in boreholes, compared to laboratory seepage tests, can bring more reliable information to estimating the in-situ seepage properties (e.g., hydraulic conductivity, intrinsic permeability, transmissivity and specific yield). In this paper, a flow-measuring technique-heat pulse flowmeter (HPFM) is methodologically introduced and then practically applied for GI in the mining extension zone of Hunter Valley Operations (HVO), New South Wales, Australia. The measuring experiences, including both positive and negative outcomes, are reported and discussed with a series of datasets of in-situ flow rates measured in the selected boreholes. The pros and cons of the HPFM application in HVO are also discussed and summarised based on the user experience collected through this field trip. Finally, through a thorough reflection, some practical recommendations are provided to help other HPFM practitioners bypass all difficulties experienced on this trip. It is anticipated that valuable user information can contribute to better GI in other sites when performing this measuring technique.

In recent years, due to the frequent occurrence of floods that exceed the facility maintenance level due to climate change, non-contact flood flow measurement techniques have been paid attention and actually some measurements have been conducted by applying them instead of the conventional float method. The space-time image velocimetry (STIV) which can measure the surface flow velocity distribution from video images is one of such techniques. In order to calculate the river flow from the surface velocity distribution, it is necessary to determine an appropriate surface velocity coefficient, which is the ratio of the average depth velocity to the surface velocity. However, at present, empirical default value has been still used in practice. In this study, the cross-sectional velocity distribution was calculated using an entropic method by utilizing the surface velocity distribution measured by STIV and compared with Acoustic Doppler Current Profiler (ADCP) observation. It was confirmed that the introduction of the velocity dip system express the flow velocity distribution in the vertical direction, where the velocity dip occurs due to the influence of vegetation.

The laminar flow meter (LFM) boasts several advantages such as no moving parts, a wide range ratio, high measurement accuracy, quick dynamic response, etc., and is a promising technology for micro gas flow measurement. In order to explore the influence of different curvature radii on curved surface gap LFM, three curved structures with different curvature radii were designed. The computational fluid dynamics method is applied to simulate the flow feature of three structures. The simulated velocity cloud and pressure distribution show that the larger the curvature radius, the more stable the flow of gas medium. The relationship between differential pressure and volume flow was obtained through the test within a flow range of 0~540 sccm. Regression analysis revealed that the volume flow measured by the curved surface LFM had a high linear relationship with the differential pressure. Experimental findings indicate that differential pressure of the structure with a curvature radius of 2 mm was greater than that of other two structures (curvature radius of 6 mm and 3 mm) at the same point. This indicates that adding the number of surfaces can effectively increase the pressure loss, so as to obtain a larger range ratio, but will increase the measurement error.