Inflow Measurements Research Articles

Doppler Tissue Imaging Is More Sensitive Than Other Echocardiographic Markers in Identifying Abnormal Relaxation in Subclinical Hypertensive Disease and Normal Ejection Fraction

This report describes the use of echocardiographic measurements for the assessment of left ventricular diastolic function in two young patients with newly diagnosed hypertension. Measurements for the assessment of left ventricular relaxation and filling pressures included mitral inflow, Doppler tissue imaging (DTI), color M-mode propagation velocity slope, and the isovolumic relaxation time. The mitral inflow, propagation velocity, and isovolumic relaxation time measurements were all within normal limits; however, DTI measurements of the E′ velocity at the septal and lateral annulus were significantly reduced in both patients. Further visual inspection demonstrated discrete proximal septal wall thickening that is thought to be modulated by pressure loading (i.e., increased afterload due to hypertension) and ejection. These findings may represent a “transitional state” of early ventricular remodeling and organ failure in the development of hypertensive disease. In summary, DTI appears to be more sensitive compared to other markers in identifying abnormal relaxation in subclinical hypertensive disease and normal ejection fraction.

A method for evaluating the evolution of clogging: application to the Pampulha Campus infiltration system (Brazil)

In order to evaluate the hydraulic performance of stormwater infiltration trenches, a study was undertaken to assess clogging and its distribution between the bottom and the sides. The method used was based on the calibration of the hydraulic resistance event by event according to Bouwer's model and applied to a demonstration trench in Belo-Horizonte monitored in the framework of the European Project Switch. The calibration was performed by minimizing the distance between measured and modeled infiltration flow rates and by using continuous measurements of rainfall, inflow, water temperature and depth in the trench. The study showed that the methodology and particularly Bouwer's model was able to produce satisfactory results. It revealed a significant clogging evolution within a year, with global resistance increasing by a factor of 9. A significant difference between the bottom and the sides was observed; the bottom being more rapidly prone to clogging. Sudden fluctuations of the hydraulic resistance of the bottom were found that could be explained by very high concentrations of total suspended solids from inflows (about 2,000 mg/L). Clogging of the sides evolves over the time but with a very low rate.

Exploring synergies and tradeoffs: Energy, water, and economic implications of water reuse in rice-based irrigation systems

Efficient use of water and energy resources are significant requirements for increasing irrigated rice productivity. However, the ever increasingly complex interplay between energy, water and agriculture in feeding both machinery and people, respectively, plus the added impact on and of climate change, have significant implications on the management of our natural resources. This paper holistically analysed a rice-dominated gravity-fed irrigation system using the Upper Pumpanga River Integrated Irrigation System (UPRIIS) in Central Luzon, the Philippines as demonstration example to quantify the water, energy and economic implications of water reuse at five different spatial scales. Water reuse was determined through daily measurements of all surface water inflows and outflows, rainfall, evapotranspiration, and the quantities of water internally reused through check dams and shallow pumping, and aggregated into seasonal totals for five spatial scales during the dry season of 2001. Energy auditing was later used to evaluate the energy implications of water reuse.Results show that ∼30% of the total surface water applied was reused by internal check dams and pumping from shallow groundwater. Across the five spatial scales, water productivity with water reuse was always higher than without water reuse, which reflects the significance of water reuse. The cost-benefit ratio indicates enhanced rice profitability at all five spatial scales with and without water reuse. However, economic benefits of water reuse were lower than economic benefits from surface water, which was mainly due to the higher costs of pumping. Irrigation requires a significant expenditure of fossil energy both for pumping and delivering water to crops. Total energy inputs of water reuse were 28% higher than the energy inputs without water reuse, which was mainly attributed to higher diesel energy inputs.Whilst water reuse contributes significantly to water productivity across the five spatial scales, it does increase energy use due to pumping. Our holistic analysis indicated a tradeoff between yield and energy use. Achieving higher water productivity would require additional use of fossil energy, which in turn could increase the energy use competition and decrease economic returns. Given the increasing global concerns about climate change and sustainable energy use, an optimal combination of water and energy use is absolutely essential.

A Stream‐Based Methane Monitoring Approach for Evaluating Groundwater Impacts Associated with Unconventional Gas Development

Gaining streams can provide an integrated signal of relatively large groundwater capture areas. In contrast to the point-specific nature of monitoring wells, gaining streams coalesce multiple flow paths. Impacts on groundwater quality from unconventional gas development may be evaluated at the watershed scale by the sampling of dissolved methane (CH4 ) along such streams. This paper describes a method for using stream CH4 concentrations, along with measurements of groundwater inflow and gas transfer velocity interpreted by 1-D stream transport modeling, to determine groundwater methane fluxes. While dissolved ionic tracers remain in the stream for long distances, the persistence of methane is not well documented. To test this method and evaluate CH4 persistence in a stream, a combined bromide (Br) and CH4 tracer injection was conducted on Nine-Mile Creek, a gaining stream in a gas development area in central Utah. A 35% gain in streamflow was determined from dilution of the Br tracer. The injected CH4 resulted in a fivefold increase in stream CH4 immediately below the injection site. CH4 and δ(13) CCH4 sampling showed it was not immediately lost to the atmosphere, but remained in the stream for more than 2000 m. A 1-D stream transport model simulating the decline in CH4 yielded an apparent gas transfer velocity of 4.5 m/d, describing the rate of loss to the atmosphere (possibly including some microbial consumption). The transport model was then calibrated to background stream CH4 in Nine-Mile Creek (prior to CH4 injection) in order to evaluate groundwater CH4 contributions. The total estimated CH4 load discharging to the stream along the study reach was 190 g/d, although using geochemical fingerprinting to determine its source was beyond the scope of the current study. This demonstrates the utility of stream-gas sampling as a reconnaissance tool for evaluating both natural and anthropogenic CH4 leakage from gas reservoirs into groundwater and surface water.

Turbine Inflow Characterization at the National Wind Technology Center

Abstract Utility-scale wind turbines operate in dynamic flows that can vary significantly over time scales from less than a second to several years. To better understand the inflow to utility-scale turbines on time scales from seconds to minutes, the National Renewable Energy Laboratory installed and commissioned two inflow measurement towers at the National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification for two utility-scale turbines. In this paper, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation, and for the persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results show that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from conditions measured at lower levels.

研究 僧帽弁および肺静脈血流の同時測定による左房容積変化-時間曲線の推定.

研究 僧帽弁および肺静脈血流の同時測定による左房容積変化-時間曲線の推定.

Characterization of skin dermis microcirculation in flow-mediated dilation using optical sensor with pressurization mechanism

Blood flows out of microvessels in the dermis when pressure higher than arterial blood pressure is applied to the fingertip, and subsequently re-flows into the microcirculation when pressure is released. Both the blood outflow and the reflow characteristics of microcirculation under pressurization are associated with microvasculature, blood and blood pressure. This study describes a novel method of measuring blood inflow and outflow characteristics of dermis microcirculation. An optical sensor, which is furnished with a 571 nm wavelength light source and a photodetector, is pressed to the skin surface using a pressure higher than the human subject's systolic arterial pressure. Hemoglobin concentration by change of the blood flow amount is estimated by the Beer-Lambert law. This method is applied to the measurement of blood inflow and outflow characteristics of microcirculation caused by reactive hyperemia after ischemia with duration of 5 min. Among three parameters evaluated, the one relating to the amplitude of pulsation shows a close correlation with conventional plethysmography, while the other two show varying time responses. Our method provides a new and useful insight into pathophysiology in health and disease conditions and may help researchers better understand the underlying mechanisms of numerous microcirculation-influenced diseases and medical conditions.

On Fluid Compressibility in Switch-Mode Hydraulic Circuits—Part II: Experimental Results

In this paper, the author presents experimental work with a generic switch-mode hydraulic circuit that aims to validate a previously presented computational model, with primary focus on the energy loss due to fluid compressibility. While multiple previous papers have presented experimental works with switch-mode hydraulic circuits, the presented experimental system is unique due the capability of in-flow measurement of the entrained air in the hydraulic fluid. A designed experiment was run that varied the entrained air, system pressure, and volume of the fluid experiencing pressure fluctuations, defined as the switched volume. The calculated volumetric efficiency from these experiments ranged from to 61% to 75%, with efficiency increasing with decreased levels of entrained air, system pressure, and switched volume. These efficiency trends and the pressure profile in the switched volume agree well with the computational model presented in Part I of this two part set (Van de Ven, 2013, “On Fluid Compressibility in Switch-Mode Hydraulic Circuits—Part I: Modeling and Analysis,” ASME J. Dyn. Sys., Meas., Control, 135(2), p. 021013). Differences between the experimental results and the computational model include approximately 10% higher predicted efficiency and pressure oscillations found in the experimental work that were not predicted by the model.

Study on Grouting Effect Evaluation of F4 Weathered Slot in Xiamen Xiang’an Submarine Tunnel

Measurement of water inflow from borehole, drilling and coring, ultrasonic inspection, ground-penetrating radar and field excavation are all used to test effect of grouting water shutoff and reinforcement in F4 weathered slot of Xiamen Xiang’an submarine tunnel. The five test ways are inter-validated to determine the grouting effect accurately and reasonably. It can provide a reliable basis for grouting design, construction and grouting effect test in similar strata. The application and development of grouting in submarine tunnel can be promoted.

The Measurement of Water Bursting Volume of Jianfeng Mountain Tunnel and Treatment Techniques of Water Bursting

The measurement of tunnel water inflow is not only an important basis for engineering design changes, but also an effective verification of design. This paper combines with the analysis of the measured data of groundwater of large water inflow section, which appeared in the construction of high-speed Jianfeng mountain super long tunnel in Fuling Fengdu, Chongqing city, and detailed information of hydrological survey results. This paper has re-evaluated the engineering geology and hydro-geological of large gushing sections to clear the reason of water inflow, the development trend characteristics of groundwater and stability of surrounding rock. It is shown in this paper that the measures such as strengthening the support parameters, optimizing the waterproof and drainaging design schemes, and other measures can be adopted to ensure the safety of tunnel construction and effectively realize the concept of dynamic construction.

The development and calibration of a generic dynamic absorption chiller model

Although absorption cooling has been available for many years, the technology has typically been viewed as a poorly performing alternative to vapour compression refrigeration. However, rising energy prices and the requirement to improve energy-efficiency is driving renewed interest in the technology, particularly within the context of combined cooling, heat and power systems (CCHP) for buildings. In order to understand the performance of absorption cooling, numerous models are available in the literature. The complexities involved in the thermodynamics of absorption chillers have, however, so far restricted researchers to creating steady-state or dynamic models reliant on data measurements of the internal chiller state, which require difficult-to-obtain, intrusive measurements. The pragmatic, yet fully dynamic model described in this paper is designed to be easily calibrated using data obtained from the measurements of inflows and outflows to a chiller, without resorting to intrusive measurements. The model comprises a series of linked control volumes featuring both performance maps and lumped mass volumes, which reflect the underlying physical structure of the device. The paper describes the modelling approach, theory and limitations, along with an example of the implementation of the model in the ESP-r code complete with calibration and an application to a specific example.

Assessment of Left Ventricular Outflow Gradient: Hypertrophic Cardiomyopathy Versus Aortic Valvular Stenosis

This study examined the relationship between peak-to-peak (common invasive measurement), peak instantaneous (common Doppler measurement), and mean pressure gradients in patients with hypertrophic cardiomyopathy (HCM) and aortic stenosis (AS).In patients with AS, the peak-to-peak gradient and peak instantaneous gradient are discrepant, and the mean gradient best represents obstruction severity. The pathophysiology of outflow obstruction differs in HCM, with the maximum gradient occurring in late systole, thus the optimal method for quantifying gradient severity in HCM remains undefined.Fifty patients with HCM and 50 patients with AS underwent gradient characterization at cardiac catheterization (age 55 ± 15 years vs. 72 ± 9 years; 48% vs. 42% male, respectively). All HCM patients were studied with high-fidelity, micromanometer-tip catheters and transseptal measurement of left ventricular inflow and central aortic pressures. In AS, simultaneous left ventricular and central aortic pressures were recorded.The peak instantaneous gradient was linearly correlated with peak-to-peak gradient in HCM (R(2) = 0.98, p < 0.0001), with the relationship close to the line of identity. In AS, more scatter and further deviation from the line of identity occurred when comparing the peak instantaneous gradient to the peak-to-peak gradient (R(2) = 0.70, p < 0.0001). Both peak-to-peak and peak instantaneous gradients were consistently higher than the mean gradient in HCM, with wide 95% confidence limits of agreement (26.7 ± 46.5 mm Hg and 16.4 ± 47.2 mm Hg, respectively).In HCM, peak instantaneous and peak-to-peak gradient demonstrate excellent correlation. Consequently, both peak instantaneous and peak-to-peak gradients can be used to classify obstruction severity in HCM. By contrast, the mean gradient should direct clinical management in AS.

Low phosphorus release but high nitrogen removal in two restored riparian wetlands inundated with agricultural drainage water

Re-established riparian wetlands used to mitigate nitrogen (N) loss from agricultural soils to surface water may lose phosphorus (P) from the top soils that often have received fertilizers. This could lead to eutrophication of lakes and estuaries. For a 2-year period we established mass balances of N and P in two restored riparian wetlands of ∼0.6ha situated on mineral soil. Monitoring began 5 years after restoration. Both wetlands received drainage water from upland agricultural fields rich in nitrate (1.5–12.3mgNL−1) and low in total P (TP) (0.016–0.04mgPL−1). Water balances were reasonably accounted for (15% imbalance at most). Water passed the wetlands as sheet flow without exchange with groundwater because of clay horizons in sub-soils, and sheet pilings along the stream banks allowed continuous measurements of inflow and outflow. The Egeskov riparian wetland (wetland:upland ratio 0.13) removed 121 and 28kgNha−1yr−1 (43 and 75% of the load) and retained 0.08kgPha−1 (6% of the load) in year one and had a net release of 0.15kgPha−1 (25% of the load) in year two. The Stor Å riparian wetland (wetland:upland ratio 0.02) removed 229 and 158kgNha−1yr−1 (32 and 26%). Net releases of P were 0.33 and 0.90kgPha−1yr−1 (22 and 127%). Nitrogen removal rates are on par with published rates for similar wetlands, while the P release rates appear surprisingly low. Phosphate outlet concentrations resembled the equilibrium concentrations (EPC0) where no phosphate exchange occurred between top soils and drainage water, suggesting that P release or retention was controlled by phosphate adsorption. This value was 0.015mgPL−1 for Egeskov and 0.047mgPL−1 for Stor Å. The high phosphate affinity was probably governed by high ratios between oxidized iron and iron-bound P. The top soils (10cm) contained 87 and 201kgPha−1 as iron-bound P and herbaceous vegetation accumulated 10.7 and 16.5kgPha−1yr−1. These figures are 55–136 and 8–11 times higher than the annual P-load to the wetlands, and we suggest that annual harvest of vegetation could maintain or even improve the P retention capacity of these wetlands.

Measurements of the rudder inflow affecting the rudder cavitation

The main objective of present study is to examine the characteristics of the complex rudder inflow(propeller slipstream) against the rudder cavitation using visualization technique. The rotating propeller of 6 blades and the semi-spade rudder are set in a medium-size cavitaion tunnel with a uniform flow condition. The rudder distorts the angle-of-attack (AoA) or incident angle to the leading edge of the rudder blade. Several methods such as uniform stream line, time-averaged velocity field and locally sampled area are proposed to analyze the AoA and show similar AoA values of 5–7° at the region of no rudder and no propeller trailing vorticity effects. However, it increases to 20° by those effects as the inflow comes to the rudder. From the AoA analysis the cavitation durability is found to be about 7° in terms of the rudder angle. Cautious access is additionally necessary to introduce a reasonable safety against those cavitation phenomena that would significantly influence the durability of the movable part.

Coupled hydrogeophysical inversion of electrical resistances and inflow measurements for topsoil hydraulic properties under constant head infiltration

ABSTRACTAccurate estimation of topsoil hydraulic properties is important for understanding water flow and solute transport in the vadose zone. Coupled hydrogeophysical inversion schemes that enable the use of multiple geophysical and hydrological data for the estimation of soil hydraulic properties have recently been proposed. In these coupled inversion schemes, a hydrological model describing the process under investigation is coupled to a forward geophysical model and hydraulic parameters are directly estimated from geophysical measurements. While these schemes provide a suitable platform for the integration of multiple geophysical and hydrological data, efficient methods to combine these data types for improved parameter estimation still warrant investigation. In this study, we investigated the feasibility of estimating three topsoil Mualem‐van Genuchten parameters from the fusion of inflow and electrical resistance measurements obtained under constant head infiltration. In addition to using only inflow or electrical resistances, we investigated three methods of combining these data for improved estimation of topsoil hydraulic parameters. Our results show that using inflow alone does not provide a unique solution to the inverse problem. Better results are obtained with the additional use of electrical resistance data. We show that successful data fusion within the coupled hydrogeophysical inversion framework depends on the choice of an appropriate objective function. We obtained the best data fusion results with an objective function defined as the sum of the root mean square error of both data types normalized by the standard deviation of the respective measurements. In this case, the inverted hydraulic parameters were very comparable to reference values obtained from a multi‐step outflow experiment carried out with undisturbed soil cores from the experimental site. It is concluded that the coupled hydrogeophysical inversion frame‐work is a promising tool for non‐invasive near‐surface hydrological investigations.

Repeatability and internal consistency of abdominal 2D and 4D PC MR flow measurements

Background We have recently demonstrated the benefits of a radially undersampled 4D-MR flow acquisition (PC-VIPR) [1,2] for angiographic imaging of the renal vasculature in humans [3] and for transstenotic pressure gradients in a swine model [4]. Validation of velocity measurements in vivo with non-MRI methods is desirable, but not possible. The purpose of this study was to assess the repeatability of 2D and 4D-PC flow measurements in humans and to assess the internal consistency of arterial in-flow and out-flow measurements in the renal vasculature.

Nitrogen transformations in a through‐flow wetland revealed using whole‐ecosystem pulsed 15N additions

We used pulsed and continuous additions of 15N together with whole‐ecosystem metabolism measurements to elucidate the mechanisms of nitrogen (N) transformations in a small (1170 m2) through‐flow wetland situated along a stream. From measurements of the wetland inflow and outflow, we observed a consistent decrease in nitrate (by 10% of inflow concentrations), while ammonium increased by an order of magnitude. Outflow ammonium concentrations oscillated in a diel cycle, inverse to the concentration of dissolved oxygen (i.e., greater ammonium export at night). The pulsed 15N additions showed little uptake of nitrate over time in the wetland and rapid daytime uptake of ammonium from the water column (rate constant, kt = 0.11 h−1). A steady‐state 15N‐ammonium addition demonstrated a similar rate of ammonium uptake (kt = 0.067 h−1), no detectable nitrification, and highlighted the spatial pattern of ammonium and nitrate uptake within the wetland. Porewater concentration profiles suggest high rates of net ammonium diffusion from the sediments. Ecosystem metabolism measurements indicate that release was attenuated during the day by autotrophic uptake, resulting in lower ammonium export during the day. Denitrification rates were modeled from dissolved N2 : Ar ratios, but they were not sufficient to account for the observed loss in nitrate. Nitrate was removed near the pond inflow but not actively cycled throughout the pond, while the balance between sediment release and subsequent uptake of ammonium from the water‐column dominated N cycling in this wetland.

Automated Quantification of Mitral Inflow and Aortic Outflow Stroke Volumes by Three-Dimensional Real-Time Volume Color-Flow Doppler Transthoracic Echocardiography: Comparison with Pulsed-Wave Doppler and Cardiac Magnetic Resonance Imaging

The aim of this study was to compare the feasibility, accuracy, and reproducibility of automated quantification of mitral inflow and aortic stroke volumes (SVs) using real-time three-dimensional volume color-flow Doppler transthoracic echocardiography (RT-VCFD), with cardiac magnetic resonance (CMR) imaging as the reference method. In 44 patients (86% of the screened patients) without valvular disease, RT-VCFD, CMR left ventricular short-axis cines and aortic phase-contrast flow measurement and two-dimensional (2D) transthoracic echocardiography (TTE) were performed. Dedicated software was used to automatically measure mitral inflow and aortic SVs with RT-VCFD. CMR total SV was calculated using planimetry of short-axis slices and aortic SV by phase-contrast imaging. SVs by 2D TTE were computed in the conventional manner. The mean age of the included patients was 40 ± 16 years, and the mean left ventricular ejection fraction was 61 ± 9%. Automated flow measurements were feasible in all study patients. Mitral inflow SV by 2D TTE and RT-VCFD were 85.0 ± 21.5 and 94.5 ± 22.0 mL, respectively, while total SV by CMR was 95.6 ± 22.7 mL (P < .001, analysis of variance). On post hoc analysis, mitral inflow SV by RT-VCFD was not different from the CMR value (P = .99), while SV on 2D TTE was underestimated (P = .001). The respective aortic SVs were 82.8 ± 22.3, 94.2 ± 22.3, and 93.4 ± 24.6 mL (P < .001). On post hoc analysis, aortic SV by RT-VCFD was not different from the CMR value (P = .99), while SV on 2D TTE was underestimated (P = .006). The interobserver variability for SV measurements was significantly worse for 2D TTE compared with RT-VCFD. RT-VCFD imaging with an automated quantification algorithm is feasible, accurate, and reproducible for the measurement of mitral inflow and aortic SVs and is superior to manual 2D TTE-based measurements. The rapid and automated measurements make this technique practical in the clinical setting to measure and report SVs routinely where the acoustic window will allow it, which was 86% in our study.

Model predictive control for wind turbines with distributed active flaps: incorporating inflow signals and actuator constraints

ABSTRACTThis paper describes the implementation of system identification and controller design techniques using model predictive control (MPC) for wind turbines with distributed active flaps for load control. An aeroservoelastic model of the 5 MW NREL/Upwind reference wind turbine, implemented in the code DU_SWAMP, is used in an industry‐based MPC controller design cycle, involving the use of dedicated system identification techniques. The novel multiple‐input multiple‐output MPC controllers, which incorporate flap actuator constraints and the use of local inflow measurement signals, are designed and implemented for various operating points. The controllers are evaluated in standard power production load cases and fatigue load reductions up to 27.3% are achieved. The distributed flaps controller scheme is also compared with simpler single‐flap single‐input single‐output and individual pitch controller schemes. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Improvement in the Assessment of Diastolic Function in a Clinical Echocardiography Laboratory Following Implementation of a Quality Improvement Initiative

The aim of this study was to demonstrate improvement in the characterization of diastolic function in the routine practice of a clinical echocardiography laboratory after the implementation of a quality improvement initiative. The echocardiographic analysis of left ventricular (LV) diastolic dysfunction is an inherently complex process involving the integration of multiple indices for accurate assessment. A baseline survey of 50 randomly chosen echocardiographic studies was reviewed for the accuracy of diastolic function assessment. A four-step quality improvement protocol was then initiated: (1) sonographer and physician education; (2) the implementation of data acquisition protocol changes using LV inflow, tissue Doppler velocity of the mitral annulus in early diastole (e'), flow propagation velocity of LV inflow (Vp), and left atrial volume index (LAVI), along with the establishment of uniform criteria for diagnostic interpretation; (3) peer review of performance; and (4) focused interactive case review sessions. At baseline, measurements of LV inflow were most often correct (100% accurate), while measurements of e' (82% accurate), Vp (12% accurate), and LAVI (12% accurate) and the proper classification of diastolic function (44% accurate) were significantly limited. After the quality improvement initiative, there were significant increases in the accuracy of all recorded measurements, with e' 92% accurate (a 10% improvement; P < .10), Vp 67% accurate (a 55% improvement; P < .001), LAVI 80% accurate (a 68% improvement, P < .001), and proper characterization of diastolic function 76% accurate (a 32% improvement, P < .001). A multifaceted quality improvement protocol including staff education, systematic support with enhanced infrastructure, and peer review with feedback can be effective for improving the clinical performance of a nonacademic echocardiography laboratory in the characterization of diastolic function.