Flow Measurements Research Articles

A study of swirl flow measurements in a cylinder under an intake flow similar to an engine operating condition using a rotating slit disk valve

A new swirl measurement system was developed by installing bevel gears and a slit rotary valve into an impulse- type swirl measurement system of the type traditionally used to measure the swirl ratio and flow coefficient of engine intake ports. When operating this new swirl measurement system, it was confirmed that the characteristics of the intake air flow rate to the cylinders were similar to those of a typical operating engine condition. When the valve lift was limited to the cam angle range of 160 to 200 (the valve lift is maximized at a cam angle of 180°), the flow coefficient Cf increased as the cam angle increased under a constant camshaft rotation speed. Moreover, as the rotation speed of the camshaft increased, the Cf value decreased slightly. The swirl ratio NR in the cam angle range of 160 to 200 showed a nearly constant value with an increase of the cam angle at a constant camshaft rotation speed. There were also no significant changes in Cf with an increase in the camshaft rotation speed. NR measurement results while changing the camshaft rotation speed cannot be obtained by the traditional impulse swirl measurement method. NR measurement results with the new swirl measurement system can be used as basic data when calculating spray dispersion characteristics considering the engine rotation speed.

A method of applying deep learning based optical flow algorithm to river flow discharge measurement

River flow discharge monitoring is one of the critical tasks performed at hydrological stations. The large-scale particle image velocimetry (LSPIV) method widely used in hydrological stations is often limited by a lack of floating objects and has a high computational complexity. The space-time image velocimetry method is susceptible to noise interference and requires high stability of the flow over time. This paper proposes a flow measurement method based on the recurrent all-pairs field transforms for optical flow (RAFT) algorithm. The 4D correlation volume pyramid in the RAFT network structure can effectively handle changing and complex flow conditions. The convolutional block attention module is introduced into the optical flow update module after the 4D correlation volume pyramid, enhancing the ability to capture complex flow surface information. Additionally, feature extraction adds deformable convolution to expand the receptive field of the flow image, which has better adaptability in non-rigid motion. To validate the effectiveness of the new method (RAFT-D-C), this paper conducts comparative experiments with both existing and new methods. The experimental results show that RAFT-D-C has relative errors of 2.13% and 4.41% for the average flow velocity of two rivers and relative errors of 2.19% and 3.05% for the total discharge, respectively. RAFT-D-C provides improved accuracy compared to other methods and requires less computational run time than the frequently used LSPIV method.

Characterization of multiphase flow through Venturi nozzle using gamma-ray tomography

Venturi-based differential pressure flow meters have proven to be robust and well suited to measure the flowrate of multiphase flow in combination with other measurement techniques. However, important challenges remain in order to reduce the effect of flow regime dependent measurement uncertainties from non-homogeneous flow.Understanding the complexities of multiphase flow through a Venturi is critical, not only for the Venturi flow measurement but also for the potential implications it might have on adjacent measurements affected by the constriction-induced flow perturbations.In this study, we examine the evolution of multiphase flow through a vertically oriented Venturi situated downstream of a T-bend, with a particular emphasis on the effects this might have on associated measurements within a multiphase metering context. Using Gamma-ray tomography, we conducted measurements at the inlet, throat, outlet, and downstream of the Venturi across a wide range of flow rates and Gas Volume Fractions (GVFs). We evaluated gas fraction (GF), slip, and cross-sectional distribution, quantified using measures of asymmetry and annularity.Our findings suggest that deviations between GF and GVF, relative slip velocity, annularity, and asymmetry are generally less at the outlet and downstream of the Venturi compared to the inlet and throat. Notably, annularity exhibits a greater impact than asymmetry on the estimation of bulk fractions from cord measurements.Overall, the study suggests that there may be more favorable conditions for measurements that require a homogeneous mix and less difference between GF and GVF at the outlet or a short distance downstream of the Venturi. However, despite the inlet results showing larger deviations due to inhomogeneous flow compared to the outlet and downstream, these results demonstrate a more predictable pattern in line with predictive models, offering potential benefits for the application of corrective models.

Patterns of water use by the Australian native Melaleuca styphelioides in urban environments and comparison of transpiration prediction by three different micrometeorological models

Key messageThe high-quality sap flow dataset of Melaleuca styphelioides could assists local councils in assessing tree water use and aids in the development of an urban tree sustainable planting management planTrees have a vital part to play in urban ecosystems, offering ecological, economic, and social advantages in addition to beautifying our suburbs. Knowledge of tree water use in urban environments is crucial for facilitating urban greening when there is a perception that growing trees on the street verge on expansive soils poses a risk to pavement and buildings. Information on long-term water use by individual trees in an urban environment is essential for local councils in developing urban tree management plans for sustainable planning of trees; however, this information is scarce. Micrometeorological models have commonly been used to estimate the canopy transpiration of plants in the absence of sap flow data. However, the reliability and accuracy of these models have rarely been assessed using sap flow measurements at the field site. This study aimed to provide the water use data of four individual Australian native Melaleuca styphelioides Sm. using sap flow instruments over 25 months. Tree transpiration, estimated based on three commonly used micrometeorological models using weather parameters and tree characteristics, was assessed and compared with sap flow measurements by employing the linear regression statistical analysis. The results revealed that the modified Penman–Monteith (PM) model demonstrated the highest level of accuracy among the evaluated models, consistently yielding lower errors and providing more reliable estimates of tree water use. This suggests that this model may be more appropriate for predicting plant water use in situations where sap flow data are unavailable.

Measurement and characteristics of radon flow in an extremely arid region based on a closed-system earth-air model

Radon (222Rn) is a radioactive gas that occurs naturally in the soil and is harmful to the environment and health. However, the measuring the amount of radon flowing is challenging. This study reveals the mechanism responsible for radon transportation and concentration variation, the main driving forces acting, and the key factors operating in the vadose zone. In this study, two separate holes were used to monitor the amount of earth-air and radon flowing in and out of the soil in the extremely arid region in China where the Mogao Grottoes are located. Using a closed-system model, the quantity, characteristics, and regularity of the flow of earth-air and radon were thus determined on daily and yearly timescales. The same patterns of variation in earth-air flow and radon concentration were found at the two sites, both depending on the variation in the atmospheric pressure (AP). When the AP decreases, earth-air flows out from the soil with a high radon concentration. Conversely, when the AP increases, earth-air enters into the soil with a low radon concentration. Thus, radon is continuously emitted from the soil. The concentration of radon in the earth-air is proportional to the rate of flow of earth-air and therefore increases as the AP decreases. The radon emission also varies with the seasonal variation in temperature and AP, which is high in summer and low in winter. On a daily timescale, the radon varies in a bimodal manner. Therefore, the net amount of radon emitted from the soil is positively correlated with the amplitude of the AP fluctuation, temperature, soil porosity, and thickness of the vadose zone. The atmospheric pumping is the main driving force responsible for the radon emission. However, the surface closure, landform, cracks, faults, grain size, pore structure, soil adsorption, basal uranium/radium, salts, wind, lunar cycle, latitude and altitude have important effects on the number of radon emission. As such, it provides a scientific basis for the effective utilization of radon and prevention of its emission from soil.

Annular impinging jets controlled by synthetic jets inducing a swirling flow character

Experimental research was conducted on an annular air jet. The active flow control was introduced by means of tangentially arranged synthetic jets. Flow visualization and measurements of the flow velocity and stagnation pressure on an impingement wall were performed. Tests were carried out with Reynolds numbers ranging from 4000 to 10,000 (evaluated from the outer exit diameter of the annular nozzle). Bistability and hysteretic effects were revealed, because two alternative flow field patterns (A and B) were identified under the same boundary conditions. In the A pattern, a small recirculation area (bubble) of separated flow was attached to the nozzle centerbody. In the B pattern, a large recirculation area of separated flow bridged the entire nozzle-to-wall distance. The effect of the Reynolds number was evaluated: the hysteresis and bistability were not observed for Re ≥ 9000. Concerning the effect of flow control, it was concluded that a moderate swirling effect can effectively suppress the hysteresis and bistability.Graphical abstract

Self-Powered Flow Rate Sensing via a Single-Electrode Flowing Liquid Based Triboelectric Nanogenerator.

Recently, triboelectric nanogenerators (TENGs) have emerged as having an important role in the next wave of technology due to their large potential applications in energy harvesting and smart sensing. Recognizing this, a device based on TENGs, which can solve some of the problems in the liquid flow measurement process, was considered. In this paper, a new method to measure the liquid flow rate through a pipe which is based on the triboelectric effect is reported. A single-electrode flowing liquid-based TENG (FL-TENG) was developed, comprising a silicon pipe and an electrode coated with a polyvinylidene fluoride (PVDF) membrane. The measured electrical responses show that the FL-TENG can generate a peak open-circuit voltage and peak short-circuit current of 2.6 V and 0.3 µA when DI water is passed through an 8 mm cell FL-TENG at a flow rate of 130 mL/min and reach their maximum values of 17.8 V-1.57 µA at a flow rate of 1170 mL/min, respectively. Importantly, the FL-TENG demonstrates a robust linear correlation between its electrical output and the flow rate, with the correlation coefficient R2 ranging from 0.943 to 0.996. Additionally, this study explores the potential of the FL-TENG to serve as a self-powered sensor power supply in future applications, emphasizing its adaptability as both a flow rate sensor and an energy harvesting device.

Effect of MRI acquisition parameters on accuracy and precision of phase-contrast measurements in a small-lumen vessel phantom

BackgroundPhase-contrast magnetic resonance imaging (PC-MRI) quantifies blood flow and velocity noninvasively. Challenges arise in neurovascular disorders due to small vessels. We evaluated the impact of voxel size, number of signal averages (NSA), and velocity encoding (VENC) on PC-MRI measurement accuracy and precision in a small-lumen vessel phantom.MethodsWe constructed an in vitro model with a constant flow rate using a 2.2-mm inner diameter plastic tube. A reservoir with a weight scale and timer was used as standard reference. Gradient-echo T1 weighted PC-MRI sequence was performed on a 3-T scanner with varying voxel size (2.5, 5.0, 7.5 mm3), NSA (1, 2, 3), and VENC (200, 300, 400 cm/s). We repeated measurements nine times per setting, calculating mean flow rate, maximum velocity, and least detectable difference (LDD).ResultsPC-MRI flow measurements were higher than standard reference values (mean ranging from 7.3 to 9.5 mL/s compared with 6.6 mL/s). Decreased voxel size improved accuracy, reducing flow rate measurements from 9.5 to 7.3 mL/s. The LDD for flow rate and velocity varied between 1 and 5%. The LDD for flow rate decreased with increased voxel size and NSA (p = 0.033 and 0.042). The LDD for velocity decreased with increased voxel size (p < 10-16). No change was observed when VENC varied.ConclusionsPC-MRI overestimated flow. However, it has high precision in a small-vessel phantom with constant flow rate. Improved accuracy was obtained with increasing spatial resolution (smaller voxels). Improved precision was obtained with increasing signal-to-noise ratio (larger voxels and/or higher NSA).Relevance statementPhase-contrast MRI is clinically used in large vessels. To further investigate the possibility of using phase-contrast MRI for smaller intracranial vessels in neurovascular disorders, we need to understand how acquisition parameters affect phase-contrast MRI-measured flow rate and velocity in small vessels.Key points• PC-MRI measures flow and velocity in a small lumen phantom with high precision but overestimates flow rate.• The precision of PC-MRI measurements matches the precision of standard reference for flow rate measurements.• Optimizing PC-MRI settings can enhance accuracy and precision in flow rate and velocity measurements.Graphical

Measuring CSF shunt flow with MRI using flow enhancement of signal intensity (FENSI).

To develop and validate a noninvasive imaging technique for accurately assessing very slow CSF flow within shunt tubes in pediatric patients with hydrocephalus, aiming to identify obstructions that might impede CSF drainage. A simulation of shunt flow enhancement of signal intensity (shunt-FENSI) signal is used to establish the relationship between signal change and flow rate. The quantification of flow enhancement of signal intensity data involves normalization, curve fitting, and calibration to match simulated data. Additionally, a phase sweep method is introduced to accommodate the impact of magnetic field inhomogeneity on the flow measurement. The method is tested in flow phantoms, healthy adults, intensive care unit patients with external ventricular drains (EVD), and shunt patients. EVDs enable shunt-flow measurements to be acquired with a ground truth measure of CSF drainage. The flow-rate-to-signal simulation establishes signal-flow relationships and takes into account the T1 of draining fluid. The phase sweep method accurately accounts for phase accumulation due to frequency offsets at the shunt. Results in phantom and healthy human participants reveal reliable quantification of flow rates using controlled flows and agreement with the flow simulation. EVD patients display reliable measures of flow rates. Shunt patient results demonstrate feasibility of the method and consistent flow rates for functional shunts. The results demonstrate the technique's applicability, accuracy, and potential for diagnosing and noninvasively monitoring hydrocephalus. Limitations of the current approach include a high sensitivity to motion and strict requirement of imaging slice prescription.

Inline automatic quality control of 2D phase-contrast flow MRI for subject-specific scan time adaptation.

To develop an inline automatic quality control to achieve consistent diagnostic image quality with subject-specific scan time, and to demonstrate this method for 2D phase-contrast flow MRI to reach a predetermined SNR. We designed a closed-loop feedback framework between image reconstruction and data acquisition to intermittently check SNR (every 20 s) and automatically stop the acquisition when a target SNR is achieved. A free-breathing 2D pseudo-golden-angle spiral phase-contrast sequence was modified to listen for image-quality messages from the reconstructions. Ten healthy volunteers and 1 patient were imaged at 0.55 T. Target SNR was selected based on retrospective analysis of cardiac output error, and performance of the automatic SNR-driven "stop" was assessed inline. SNR calculation and automated segmentation was feasible within 20 s with inline deployment. The SNR-driven acquisition time was 2 min 39 s ± 67 s (aorta) and 3 min ± 80 s (main pulmonary artery) with a min/max acquisition time of 1 min 43 s/4 min 52 s (aorta) and 1 min 43 s/5 min 50 s (main pulmonary artery) across 6 healthy volunteers, while ensuring a diagnostic measurement with relative absolute error in quantitative flow measurement lower than 2.1% (aorta) and 6.3% (main pulmonary artery). The inline quality control enables subject-specific optimized scan times while ensuring consistent diagnostic image quality. The distribution of automated stopping times across the population revealed the value of a subject-specific scan time.

Carbon Emission Accounting Model for Comprehensive Medical Facilities Based on Population Flow

China is striving to reach a peak in its carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060. The accurate accounting of carbon emissions is important for achieving these dual carbon goals. An extensive literature review and field measurements were conducted to investigate the specific impact of population density on carbon emissions in large integrated healthcare organizations. This research uses VOSviewer to visualize the literature analysis. We determined that the flow of people is a key factor affecting carbon emissions during the operational phase of large-scale comprehensive medical institutions. Through field measurements, the relationship between the density of pedestrian flow and indoor environment measurements was derived, and the incremental equipment operating loads caused by changes in the indoor environment were analyzed. Using the carbon emission factor method advocated by the IPCC, a carbon emission accounting model based on different flow intervals was constructed, and the energy consumption of different equipment was fully considered according to its proportion. The validation results showed that the error between the calculated value and the actual values of the model was 3.07% (less than 5%), which has good validity. The model calculates the direct and indirect carbon emissions in the operational phase based on the population flow perspective, which can provide a reference for the energy-saving design and green operation of large-scale comprehensive medical institutions. The research will continue to focus on the population flow, and the accounting model will be further optimized through machine learning algorithms.

An indirect flow measurement method for bi-tandem axial piston pump based on leakage flow estimation

In pump-controlled hydraulic systems, configuring a flowmeter at a variable piston pump to monitor output flow causes additional losses. A method for indirect flow measurement of the bi-tandem axial piston pump based on flow leakage estimation is proposed to address this problem. The method first installs a displacement transducer at the actuator piston to collect data on the actuator piston position, outlet pressure, and shaft speed, then estimates leakage of key kinematic pairs, and finally considers flow ripple and fluid compressibility to form an indirect measurement for output flow of the pump. The indirect measurement accuracy under various typical operating conditions is analyzed. The results demonstrate that the mean absolute percentage error of the proposed indirect flow measurement method is less than 2.10%, and the method is effective with high measurement accuracy. The indirect measurement method avoids extra costs and energy consumption associated with configuring flowmeters in engineering hydraulic systems.

ComPipe: A Novel Flow Placement and Measurement Algorithm for Programmable Composite Pipelines

Programmable networks comprise heterogeneous network devices based on both hardware and software. Hardware devices provide superior bandwidth and low latency but encounter challenges in managing large table entries. Conversely, software devices offer abundant flow tables but have a limited forwarding capacity. To overcome this limitation, some commercial switches offer implementations that combine both hardware and software devices. In this context, this paper presents the Composite Pipeline (ComPipe), an algorithm for high-performance and high-precision flow placement and measurement. ComPipe utilizes a multi-level hashing algorithm for the real-time identification of heavy hitters, incorporates a unique flow eviction strategy, and is implemented on commercial programmable hardware. For non-heavy flows, ComPipe employs sketch structures to accomplish a high-performance flow synopsis within limited memory constraints. This design allows to replace flow rules entirely in the data plane, ensuring the timely detection and offloading of heavy-hitter flows, and offering a unified interface to the controller. The ComPipe prototype has been implemented in both testbed and simulation environments. The results indicate that ComPipe is an effective solution for dynamic flow placement in programmable networks, distinguished by its low cost, high performance, and high accuracy.

A highly stable, pressure-driven, flow control system based on Coriolis mass flow sensors for organs-on-chips

Stable delivery of liquids to microfluidic systems is essential for their reproducible functioning, especially when supplying flows to organs-on-chips – delicate living models that recreate human physiology on the microscale and thus can be used to reduce the need for animal testing. Most flow control systems are unable to sustain a robust and stable flow in longer experiments (>1 week), particularly those based on the ubiquitous syringe pump. Though easy to use, syringe pumps have no mechanism for actually measuring flow, let alone flow regulation with sensor feedback. We have developed a liquid delivery system based on the generation of flow by applying a constant air pressure to liquids in sealed containers. A flow of liquid is monitored by accurate measurement of mass flows (mg/min) using downstream Coriolis-based mass flow sensors. Measured mass flows provide fast feedback to integrated valves, with valves opening or closing slightly to increase or decrease solution flows to the organs-on-chips as required. This mass flow sensing principle is not affected by changes in the density, temperature, and viscosity of the liquids being displaced. This is in contrast to systems that use volumetric flow sensors, which require recalibration when these parameters change. The rationale behind using this principle for organs-on-chips, is that the stability provided by this flow control system allows for more control over growth of these mini-organs. We demonstrate the functionality of this system with three examples: 1) Fast stabilization (within seconds) under changing physical conditions; 2) Short-term stability (minutes to hours) of delivered flows in a microreactor with interconnected inlets; and 3) Long-term stability (>1 week) of cell medium flows to a living organ-on-a-chip. Two categories of organs-on-chips (OOCs) can be distinguished: 1) solid OOC are designed for three-dimensional cell or tissue constructs that interact with each other and their surroundings, and 2) barrier-type OOC contain a selective cellular barrier between two compartments as do many barriers in the body. The latter of these two types is the most challenging to culture and maintain as they are very sensitive to variations in flow and pressure surges. The flow control system presented in this work provides a great improvement compared to the use of syringe pumps and volumetric flow sensors in OOC studies. The novelty of this work lies in the long-term stability use of this system for organs-on-chips, maintaining stability for short to very long periods of time without compromising the barrier function of the organ-on-chip by pressure surges, bacterial contamination, or other undesired effects from the flow delivery system.

Flow rate measurements of slug flow by pressure differences of a venturi tube with a swirler

When the elongated bubbles and liquid slugs of slug flow alternately flow through a throttling element, the strong random fluctuations of pressure difference leads to low accuracy of online measurement of gas-liquid flow rates. In this paper, slug flow is converted into an annular flow before entering a venturi tube using a swirler, and the pressure fluctuation amplitude of the gas-liquid two-phase flow is greatly reduced, and the linear correlation between the pressure difference and the gas-liquid flow rates is more significant. The effects of gas-liquid flow rates on the axial pressure difference ΔPs across the swirler, the radial pressure difference ΔPr on a cross-section downstream of the swirler and the axial pressure difference ΔPo of the venturi tube were studied under the condition of 40%–82% gas volume fraction. The square root of the pressure difference increases linearly with the liquid/gas flow rate, and the empirical correlations between the square root of the pressure differences and the gas-liquid flow rates are established. By combining the empirical correlations in pairs, three flow rates measurement models of slug flow based on double pressure differences are established. When ΔPo and ΔPs are used as the measurement parameters of flow rates, the relative errors of liquid-phase flow rate and gas-phase flow rate are below ±2% and ±15%, respectively. When ΔPo and ΔPr are used as the measurement parameters of flow rates, the relative errors of liquid-phase flow rate and gas-phase flow rate are below ±3% and ±15%, respectively. It provides high-precision, low-cost and non-radioactive two-phase flow measurement technology for oil-gas gathering and transportation.

Association between patent ductus arteriosus flow and home oxygen therapy in extremely preterm infants

BackgroundCentral blood flow measurements include the estimation of right and left ventricular output (RVO, LVO), superior vena cava (SVC) flow, and calculated patent ductus arteriosus (PDA) flow. We aimed to provide an overview of the maturation patterns of these values and the relationship between PDA flow and the need for home oxygen therapy.MethodsThis prospective single-center study was conducted in infants born at <26 weeks of gestation. We performed echocardiographic measurements five times during their life (from the 4th post-natal day to the 36th postmenstrual week).ResultsSixty patients with a mean birth weight of 680 (590, 760) g were included. Postnatal development of LVO and PDA flow peaked at the end of the second postnatal week (427 and 66 mL/kg/min, respectively). The RVO increased between days 4 and 7–8. The SVCF was most stable. The development curves of PDA flow differed between the groups with (n = 28; 47%) and without home oxygen therapy.ConclusionWe present the central blood flow values and their postnatal development in infants <26 weeks of gestation. This study demonstrates the association between PDA flow and the future need for home oxygen therapy.ImpactThis study enriches our knowledge of the long-term development of central blood flow parameters and derived patent ductus arteriosus (PDA) flow in extremely preterm infants (<26 weeks).While pulmonary resistance decreased, PDA flow continued to increase from day 4 to the end of the second week of life. Similarly, left ventricular output increased as a marker of preload. The superior vena cava flow remained stable.The observed association between PDA flow and an unfavorable respiratory outcome is important for future studies focusing on the prevention of chronic lung disease.

Particle Image Velocimetry and Total Temperature Characterization of Arc-Heated Mach 4.5 Free Jet

Particle image velocimetry (PIV) measurements were conducted in the Arc-Heated Combustion Tunnel (ACT-II) on a high-enthalpy Mach 4.5 nozzle flow. The primary motivation for the current work is to establish the feasibility of PIV as a high-quality flow diagnostic technique in hypersonic arc-heated flows and produce a high-resolution hypersonic nozzle flow characterization, including nozzle free jet shear layer velocity profiles. Due to the uncertain nature of the gas composition in the flowfield of interest, PIV measurements of a supersonic wedge flow were used to couple the flow velocities to the oblique shock relations. This enabled a PIV-derived total temperature calculation that does not require a priori assumptions of the exact gas composition. A PIV expansion module was developed for this study, and proper seed sizing and material were selected for the present flow. An analysis of the seed particle response from the PIV measurements provided an initial validation of the seed performance while revealing potential issues with consistent seed sizing. These measurements and derived conditions represent a means of acquiring high-resolution velocimetry and temperature datasets that consider uncertainties in the experimental generation of hypersonic high-enthalpy flows.

ENERGY EFFICIENCY IN AGROFORESTRY PARCELS IN ALLUVIAL MINING AREAS UNDER ECOLOGICAL SUCCESSION IN THE MUNICIPALITY OF EL BAGRE - ANTIOQUIA (COLOMBIA)

&lt;p&gt;&lt;strong&gt;Background.&lt;/strong&gt; The agroforestry parcels are processes of ecological succession that, through technical activities applied to the soil, the areas intervened by the intensive mining operation of deep alluvium are recovered and adapted to biodiverse areas that transform the intervened landscape into productive and environmentally healthy areas with a very marked concept towards family farming. &lt;strong&gt;Objective.&lt;/strong&gt; To analyze the energy efficiency in the production of agroforestry plots located in alluvial mining areas in processes of ecological succession, in the municipality of El Bagre - Antioquia. &lt;strong&gt;Methodology.&lt;/strong&gt; A field evaluation was carried out in the "agroforestry parcels" located in the municipality of El Bagre, department of Antioquia - Colombia. A sustainability analysis was carried out through the evaluation of indicators and complementary methods such as the rapid evaluation of biodiversity (Institute for Plant Health Research - INISAV, Havana, Cuba), measurement of energy flows and uses, and the application of the Shannon index, as indicators of diversity. &lt;strong&gt;Results.&lt;/strong&gt; The findings of this research show the level of energy efficiency of each studied agroforestry parcel and the agroecological characteristics, in terms of sustainability and resilience of the restored areas in the agricultural context of the region. &lt;strong&gt;Implications.&lt;/strong&gt; Defining the recovery process of other agroforestry parcels as a successful experience based on the evaluation of agroecology principles, that is, relations of production, society and culture, among other dimensions, can become a tool applicable to the evaluation of recovery processes of ecosystems intervened and degraded by extractive mining practices and support agricultural planning processes. &lt;strong&gt;Conclusions.&lt;/strong&gt; These conservation and recovery processes of soils affected by mining may show positive transformations that respond to ecological principles, and this can be demonstrated through the evaluation of sustainability indicators.&lt;/p&gt;

V Flow Measurements of Pulsatile Flow in Femoral-Popliteal Bypass Proximal Anastomosis Compared with CFD Simulation

This paper presents the experience of using the V Flow high-frame-rate ultrasound vector imaging method to study the pulsatile velocity fields in the area of the proximal anastomosis for femoral popliteal bypass surgery in vitro and in vivo. A representative (average) anastomosis model and the experimental setup designed for in vitro studies covering forward and reverse flow phases throughout the cycle are described. The results of the measurements are presented for areas with a relatively uniform velocity distribution and for areas with pronounced spatial inhomogeneities due to the jet or recirculating nature of the flow. The results of ultrasonic studies of the velocity field of the three-dimensional pulsatile flow in vitro and in vivo are compared with the data of numerical simulations carried out for the average and personalized models based on the Navier–Stokes equations. Acceptable consistency between the results of experimental and numerical studies is demonstrated.

Measurement and analysis of void fraction in horizontal plug flow based on electromagnetic wave sensor

Void fraction measurement is a crucial challenge in two-phase flow, which is related to the measurement of phase flow and the calculation of pressure drop. In this study, a coaxial line phase sensor is designed for void fraction acquisition and the void fraction of the plug measured has a well time-domain and Probability Density Functions (PDF) distribution characteristics. Four typical correlations were selected to compare with the measured values of the sensors, the mean absolute errors (MAPE) are 19.88 %, 18.94 %, 18.25 %, and 17.19 %, respectively. Considering the nonlinear and strong coupling between the flow characteristic parameters and the void fraction, the flow parameters were analyzed and selected by Pearson correlation coefficient. The Kernel ridge regression methods were employed to select effective variables for model training, and the Extreme gradient boosting (XGboost) machine learning model was proposed. The prediction accuracy of the model is 1.65 % (current data) and 4.18 % (literature data), respectively.