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Systematic research into device-induced red blood cell (RBC) damage beyond hemolysis, including correlations between hemolysis and RBC-derived extracellular vesicles, remains limited. This study investigated non-physiological shear stress-induced RBC damage and changes in related biochemical indicators under two blood pump clinical support conditions. Pressure heads of 100 and 350 mmHg, numerical simulation methods, and two in vitro loops were utilized to analyze the shear stress and changes in RBC morphology, hemolysis, biochemistry, metabolism, and oxidative stress. The blood pump created higher shear stress in the 350-mmHg condition than in the 100-mmHg condition. With prolonged blood pump operation, plasma-free hemoglobin and cholesterol increased, whereas plasma glucose and nitric oxide decreased in both loops. Notably, plasma iron and triglyceride concentrations increased only in the 350-mmHg condition. The RBC count and morphology, plasma lactic dehydrogenase, and oxidative stress across loops did not differ significantly. Plasma extracellular vesicles, including RBC-derived microparticles, increased significantly at 600 min in both loops. Hemolysis correlated with plasma triglyceride, cholesterol, glucose, and nitric oxide levels. Shear stress, but not oxidative stress, was the main cause of RBC damage. Hemolysis alone inadequately reflects overall blood pump-induced RBC damage, suggesting the need for additional biomarkers for comprehensive assessments. [ABSTRACT FROM AUTHOR]

A new analytical solution is developed to calculate the hydraulic emission uniformity (EUh) of horizontal tapered drip laterals. Our methodology builds upon normalizing the pressure head profiles along each segment of the lateral. Results indicated that the EUh remains fairly consistent regardless of the total lateral length if a fixed pressure head tolerance (δ) is assigned in the design process. Instead, the EUh is primarily influenced by the number of emitters on each segment, their diameter ratio, and the emitter exponent x. Employing tapered laterals for any given values of δ and x enhances energy conservation compared to using single diameter laterals. However, it may lead to a reduction in the EUh , particularly when the number of emitters in the smaller diameter segment is low relative to the total number of outlets. It was concluded that the coefficient of variation in emitter pressure heads CV and EUh exhibit a nonlinear behavior in the case of tapered laterals, whereas it has been previously established as linear for single diameter laterals. Interestingly, when applying the newly formulated relationships for EUh and CV while keeping the same diameter for both segments, the results align with those previously obtained for single diameter laterals. Validation of the proposed EUh model against the precise stepwise solution revealed a maximum absolute relative error of ≈1%. When excluding the fully laminar flow condition (x=1), relative errors typically remained below 0.5%. The proposed model could serve as a foundational framework for designing tapered laterals to achieve a targeted uniformity level in future studies. [ABSTRACT FROM AUTHOR]

The current techniques utilized for estimating seasonal fluctuations in earthing system resistance, including artificial neural networks (ANNs) and correlation/correction factors, rely on resistance records, soil resistivity measurements, and meteorological data collected across broad areas. However, they frequently fail to consider the impact of soil conditions and properties at the actual earthing location. As a solution, this research introduces a new method that models atmospheric conditions as soil suction and incorporates hydraulic soil properties (soil water retention characteristics and hydraulic conductivity) to estimate the seasonal changes in earthing resistance and performance. To illustrate this approach, this study constructs geometric models of vertical earthing rods for three homogeneous soil textures (clayey, silty, and sandy) utilizing COMSOL Multiphysics software. By coupling the differential equations governing electric current and water flow using Archie's formula and solving numerically with the finite element method (FEM) for various soil suctions, this research reveals that soil water retention and resistivity variations are notably influenced by soil texture. Sandy soil displays higher variability, silt soil demonstrates moderate changes, while clayey soil exhibits lower fluctuation. By linking soil resistivity changes to soil suction and hydraulic properties, this innovative method predicts seasonal trends in earthing resistance and performance. [ABSTRACT FROM AUTHOR]

The pipe component of a water distribution network (WDN) is sized based on the fixed design demand considering a peak factor and design period. Simulation of the designed network by a hydraulic solver provides nodal pressure head, head loss, velocity, and flow in each pipe as the prime outputs for the design demand, and it can also be used for extended-period simulation for a particular demand pattern over the supply hours. But, in reality, the behavior of the network does not match with such a result in an intermittent water supply (IWS) system due to the fact that all house service connections behave as an uncontrolled orifice. This has made it a challenging task in understanding and in predicting the behavior of the networks by the municipal engineer once the water starts flowing through the house service connections (HSCs). Though the municipal engineer provides the same pipe size for HSCs to all residences, the flow received by each house could vary based on the available pressure head at the ferrule point of the main water supply pipeline. In reality, maintaining constant pressure at each HSC is not feasible due to frictional head loss. Hence, variation in flow at the HSC is inevitable even with a small water supply system. This paper illustrates how to simulate the behavior of an IWS system based on the number of HSCs provided to each pipeline using a hydraulic solver. Hydraulic simulation of the water distribution network that provides IWS to consumers can be implemented easily by adding a fictitious node by assigning an appropriate emitter coefficient to each demand node through a fictitious link having a check valve in it. The method for finding the appropriate value of the emitter coefficient that helps in simulating HSCs is illustrated in the present work. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid leak localization approach in WDNs is proposed, combining both model-based and data-driven modeling. Pressure heads of leak scenarios are simulated using a hydraulic model, and then used to train a machine-learning-based leak localization model. A key element of the methodology is that discrepancies between simulated and measured pressures are accounted for using a dynamically calculated bias correction, based on historical pressure measurements. Data of in-field leak experiments in operational water distribution networks were produced to evaluate our approach on realistic test data. The results show that the leak localization model is able to reduce the leak search region in parts of the network where leaks induce detectable drops in pressure. When this is not the case, the model still localizes the leak but is able to indicate a higher level of uncertainty with respect to its leak predictions. HIGHLIGHTS Hydraulic modeling and machine learning were combined in a hybrid WDN leak localization approach.; Data sets of real in-field leak experiments were created and made publicly available, as well as code used.; Experimental leaks were localized with adaptive levels of uncertainty.;

Ventricular assist devices (VADs) are implantable turbomachines that save and improve the lives of patients with severe heart failure. In the preclinical evaluation, a VAD design must be experimentally or numerically tested regarding its pump characteristics, primarily for its pressure buildup (pressure head  H) since it must provide the cardiovascular system with a sufficient blood flow rate  Q. Those pump characteristics are determined on a test bench. Here, a glycerol-water mixture is almost exclusively used as blood-analogous fluid, which should reflect the properties (density, viscosity) of blood as close as possible. However, glycerol water has some disadvantages, such as a higher density compared to real blood and a relatively high cost. Therefore, the study aimed to analyze six different blood analogous fluids to select the most suitable one in consideration of fluid handling, costs, and, most importantly, fluid properties (material and rheological). First, all fluids were mixed to achieve reference values of blood density and viscosity from the literature. Afterwards, the pump characteristics (pressure heads and efficiencies via the VAD) were experimentally and numerically determined and compared among each other and with literature values. Of all six investigated fluids, only the aqueous–polyethylene glycol 200 (PEG 200) solution matches exactly the desired blood properties, and the pump characteristics of this fluid are in the expected range for the analyzed operation point of the VAD. Another advantage is that the cost of the mixture is 35% lower compared to glycerol water. Additionally, we demonstrate that non-Newtonian flow behavior has little effect on the pump characteristics in our VAD. [ABSTRACT FROM AUTHOR]

Downstream of the sluice gate or weir, wave-type flows inevitably occur in stilling basins with no tailwater. This paper aims to investigate the hydraulic performance of wave-type flows at a sill-controlled stilling basin through experimental research. The flow pattern, bottom pressure profiles along the stilling basin, and the air concentrations on the bottom and the sidewall were examined in five sill-controlled stilling basins by altering the sill position and the height. The results show that wave-type flow patterns contain submerged and non-submerged jumps, which are relevant to ambient pressure head and air entrainment. The bottom pressure profiles are related to larger pressure fluctuations at large unit discharges and two peak pressure values in the vicinity of the sill. The air concentrations on the bottom and the sidewall decrease with the increasing unit discharge. The flow zone in the vicinity of the sill should be focused upon concerning protection against cavitation damage because of the slight air entrainment and significant pressure fluctuations. These findings advance our understanding of wave-type flows, and their ambient pressure heads and air entrainment are useful for designing the sill-controlled stilling basin in hydraulic engineering. [ABSTRACT FROM AUTHOR]

The soil water retention curve is the fundamental soil hydraulic property to characterize soil water movement and solute transport. Many efforts have been devoted in the past decades to developing models to describe soil water retention curves. However, most of them are empirical equations or assume that soil pore size distributions conform to a lognormal distribution. Yet, few effects have been undertaken to systematically propose and compare a series of possible alternative probability density functions to describe the sigmoid retention curves with parameters physically explainable. Here, we proposed a family of five soil water retention models based on sigmoid functions with parameters of clear physical implications coinciding with the statistical measures of soil pore size distribution. Compared with the widely used models (i.e., Brooks & Corey, 1964; Kosugi, 1996; van Genuchten, 1980), the proposed models have somewhat improved performances to characterize water retention data for a wide range of soil textures without introducing additional model parameters. Two of the proposed models are capable of characterizing the observed two local extrema in the moisture capacity curves. The associated unsaturated hydraulic conductivity models of the proposed soil water retention models are also derived, which show superior performance in characterizing the observed hydraulic conductivities compared with competing models, especially in macropore regimes. Additionally, we analyzed the parameter‐equivalent conversion between the proposed and the existing models, and a simple linear regression equation can be used to derive the parameters of the proposed models from the existing and other alternative different proposed models. Key Points: A family of soil water retention models based on sigmoid functions and related relative hydraulic conductivity functions are proposedParameters have statistical implications against pore size distributions and can be converted from existing or alternative new modelsCharacterization of hydraulic properties is improved using new models, especially for macropore properties, without additional parameters [ABSTRACT FROM AUTHOR]

Seepage is a dangerous phenomenon under hydraulic structures and the main cause of failure and damage to dams when neglected and not processed. This study evaluates the numerical effects of the sheet piles' quantity, depth, and spacing beneath a concrete dam with isotropic and homogenous foundations on the seepage rate, pressure head, and exit gradient. The solutions were obtained using SEEP/W code in GeoStudio software 2018 for three configurations using single, double, and triple sheet piles. In addition, SLIDE software 6.02 was examined using single and double sheet piles. Dimensional analysis was applied to draw the dimensionless variables that affect the seepage rate and exit gradient, and all tests were repeated for three different sheet pile depths and distances from the heel of the dam. The findings showed that the seepage rate in all studied configurations reduced when sheet pile depth increased. The position of the sheet pile from the dam's toe significantly decreased the seepage rate in cases using single and double sheet piles, while in cases using three-sheet piles, the position of the middle sheet pile insignificant decreased seepage. It was recognized that when using a single sheet pile, the drop in pressure head increased with depths when the sheet pile was located at the heel and middle of the dam. In addition, in the case of a single sheet pile at the toe or using two and three-sheet piles, the pressure drop decreased as the depths increased. Also, the results showed that the middle sheet pile location in the case of three sheet piles slightly affected pressure reduction. Furthermore, the results showed that using two and three-sheet piles was more effective than using a single one in reducing the exit gradient, while the position of the middle one in the case of using three-sheet piles was insignificant. A nonlinear empirical equation was developed using SPSS 22 program, and the comparison of the seepage rate measured by SEEP/W and SLIDE software versus its quantity calculated from empirical equations showed a good agreement as the determinations (R2) coefficients were equal to 0.9779 and 0.9928, respectively.

The current techniques utilized for estimating seasonal fluctuations in earthing system resistance, including artificial neural networks (ANNs) and correlation/correction factors, rely on resistance records, soil resistivity measurements, and meteorological data collected across broad areas. However, they frequently fail to consider the impact of soil conditions and properties at the actual earthing location. As a solution, this research introduces a new method that models atmospheric conditions as soil suction and incorporates hydraulic soil properties (soil water retention characteristics and hydraulic conductivity) to estimate the seasonal changes in earthing resistance and performance. To illustrate this approach, this study constructs geometric models of vertical earthing rods for three homogeneous soil textures (clayey, silty, and sandy) utilizing COMSOL Multiphysics software. By coupling the differential equations governing electric current and water flow using Archie’s formula and solving numerically with the finite element method (FEM) for various soil suctions, this research reveals that soil water retention and resistivity variations are notably influenced by soil texture. Sandy soil displays higher variability, silt soil demonstrates moderate changes, while clayey soil exhibits lower fluctuation. By linking soil resistivity changes to soil suction and hydraulic properties, this innovative method predicts seasonal trends in earthing resistance and performance.

Purpose: The design and optimization of centrifugal blood pumps are crucial for improved extracorporeal membrane oxygenation system performance. Secondary flow passages are common in centrifugal blood pumps, allowing for a high volume of unstable flow. Traditional design theory offers minimal guidance on the design and optimization of centrifugal blood pumps, so it's critical to understand how design parameter variables affect hydraulic performance and hemocompatibility. Methods: Computational fluid dynamics (CFD) was employed to investigate the effects of blade number, blade wrap angle, blade thickness, and splitters on pressure head, hemolysis, and platelet activation state. Eulerian and Lagrangian features were used to analyze the flow fields and hemocompatibility metrics such as scalar shear stress, velocity distribution, and their correlation. Results: The equalization of frictional and flow losses allow impellers with more blades and smaller wrap angles to have higher pressure heads, whereas the trade‐off between the volume of high scalar shear stress and exposure time allows impellers with fewer blades and larger blade wrap angles to have a lower HI; there are configurations that increase the possibility of platelet activation for both number of blades and wrap angles. The hydraulic performance and hemocompatibility of centrifugal blood pumps are not affected by blade thickness. Compared to the main blades, splitters can improve the blood compatibility of a centrifugal blood pump with a small reduction in pressure head, but there is a trade‐off between the length and location of the splitter that suppresses flow losses while reducing the velocity gradient. According to correlation analysis, pressure head, HI, and the volume of high shear stress were all substantially connected, and exposure time had a significant impact on HI. The platelet activation state was influenced by the average scalar shear stress and the volume of low velocity. Conclusion: The findings reveal the impact of design variables on the performance of centrifugal blood pumps with secondary flow passages, as well as the relationship between hemocompatibility, hydraulic performance, and flow characteristics, and are useful for the design and optimization of this type of blood pump, as well as the prediction of clinical complications. [ABSTRACT FROM AUTHOR]

The 2018 Hokkaido Eastern Iburi Earthquake triggered numerous shallow landslides on slopes covered with thick pyroclastic-fall deposits. The landslides occurred more frequently on concave slopes than on convex slopes, implying that water was responsible for initiating them. As a first step toward clarifying the role of water in such landslides, we monitored the pressure-head (ψ) dynamics of uncollapsed concave and convex slopes and measured the hydraulic properties of each layer in the laboratory. Our results show that while the lower part of the pyroclastic-fall-deposit layers and the weathered basement complex (sedimentary rock) are always at or near saturation with little relationship to rainfall on concave slopes, the weathered basement complex never becomes saturated and shows greater fluctuation in ψ on convex slopes. From these results and the hydraulic properties, it can be inferred that water plays two important roles in co-seismic landslides: the formation of a pyroclastic-fall-deposit layer that is vulnerable to seismic motions as a result of persistently promoted weathering, and the saturation of the depths around a landslide slip surface just before earthquake onset. These factors allow sliding-surface liquefaction to be induced by earthquakes and also explain why co-seismic landslides occur more frequently on concave slopes. It was also inferred that 11 mm of rainfall 25–27 h prior to earthquakes has little effect on landslide initiation, as similar rainfall amounts do not affect ψ around a slip surface. [ABSTRACT FROM AUTHOR]

In the event of a rainfall, the contrast in hydraulic conductivity and shear strength properties of a layered soil can be significant in determining the stability of a slope. The main objectives of this study were to model 1-D infiltration into a two-layered soil formation and to understand the effect of contrast in the permeability characteristics of the two layers on failure depth, time, and mechanism, in the event of a shallow landslide. Two hypothetical soils-relatively coarse and fine soils-were assumed for the layered soil model. 1-D infiltration into a partially saturated soil was modelled through the development of a finite difference numerical scheme by solving the mixed form of Richard's equation. The stability analysis has been conducted for varying rainfall intensities and permeabilities using a pre-defined stability envelope based on the pressure head. For the case where fine soil overlies the coarse soil in a two-layered model, results showed that the failure depth is significantly reduced when the saturated permeability of coarse soil decreases relative to the fine soil. The only possible failure mechanism was identified as 'loss of suction'. When the coarse soil overlain by a fine soil, no significant effect on failure depth has been observed. Both 'loss of suction' and the development of a 'perched water table' were identified as possible mechanisms. In both cases, it was noticed that the failure time decreases as the saturated permeability of coarse soil increases. The results suggest that contrast in permeability characteristics in layered soil formations plays a vital role in influencing failure time, depth, and mechanism. [ABSTRACT FROM AUTHOR]

The article is devoted to a pilot study of the reverse-bladed pump. The characteristics of the reverse bladed pump are the identical parameters on flow, the head, power, energy efficiency on direct and the return operating modes (at rotation of a rotor of the pump both in one and to the opposite side). The model reversible axial pump with two impeller versions was tested on an experimental bench. The impellers were distinguished by the shape of the profile in the blade sections. The model reversible pump was structurally a reversible axial impeller placed in a cylindrical chamber. Studies were carried out at different angles of rotation of the impeller blades. The power characteristics of tested versions of the pump (impeller) at the design and under loading (unstable operation) modes are given. Low efficiency of the tested versions of the reversible pump compared to the conventional axial pumps is noted, primarily due to the strong influence of the secondary gradients of the pressure factor. The second reason is the profile separation of the flow from the blade surface, to which the tested reverse pump screens are predisposed.

Ventricular assist devices (VADs) are implantable turbomachines that save and improve the lives of patients with severe heart failure. In the preclinical evaluation, a VAD design must be experimentally or numerically tested regarding its pump characteristics, primarily for its pressure buildup (pressure head H) since it must provide the cardiovascular system with a sufficient blood flow rate Q. Those pump characteristics are determined on a test bench. Here, a glycerol-water mixture is almost exclusively used as blood-analogous fluid, which should reflect the properties (density, viscosity) of blood as close as possible. However, glycerol water has some disadvantages, such as a higher density compared to real blood and a relatively high cost. Therefore, the study aimed to analyze six different blood analogous fluids to select the most suitable one in consideration of fluid handling, costs, and, most importantly, fluid properties (material and rheological). First, all fluids were mixed to achieve reference values of blood density and viscosity from the literature. Afterwards, the pump characteristics (pressure heads and efficiencies via the VAD) were experimentally and numerically determined and compared among each other and with literature values. Of all six investigated fluids, only the aqueous–polyethylene glycol 200 (PEG 200) solution matches exactly the desired blood properties, and the pump characteristics of this fluid are in the expected range for the analyzed operation point of the VAD. Another advantage is that the cost of the mixture is 35% lower compared to glycerol water. Additionally, we demonstrate that non-Newtonian flow behavior has little effect on the pump characteristics in our VAD.

Downstream of the sluice gate or weir, wave-type flows inevitably occur in stilling basins with no tailwater. This paper aims to investigate the hydraulic performance of wave-type flows at a sill-controlled stilling basin through experimental research. The flow pattern, bottom pressure profiles along the stilling basin, and the air concentrations on the bottom and the sidewall were examined in five sill-controlled stilling basins by altering the sill position and the height. The results show that wave-type flow patterns contain submerged and non-submerged jumps, which are relevant to ambient pressure head and air entrainment. The bottom pressure profiles are related to larger pressure fluctuations at large unit discharges and two peak pressure values in the vicinity of the sill. The air concentrations on the bottom and the sidewall decrease with the increasing unit discharge. The flow zone in the vicinity of the sill should be focused upon concerning protection against cavitation damage because of the slight air entrainment and significant pressure fluctuations. These findings advance our understanding of wave-type flows, and their ambient pressure heads and air entrainment are useful for designing the sill-controlled stilling basin in hydraulic engineering.

The straw composite pipe is a permeable pipe made of straw and soil as the main raw materials, which can replace the field capillary for underground irrigation. In order to provide reference for the design and application of straw underground irrigation system, the working pressure and drying time were used as experimental factors to study the effects of working pressure, pressure increasing process, depressurization process and drying time on the water permeability of straw composite pipe under the condition of free outflow. Influence. The results show that: under the condition of free outflow, the cumulative water seepage amount of the straw composite pipe increases with the increase of the working pressure, and the cumulative water seepage amount has a power function relationship with the water seepage time. The water seepage process of the straw composite pipe can be fitted by the Philip infiltration formula; When the working pressure head is 10-50 cm, the water seepage of the straw composite pipe is 0.6-3.6 L/(m h); the steady water seepage rate has a linear relationship with the working pressure. The uniform coefficient of water seepage after the composite pipe reaches stable water seepage is all above 0.85; the pressure rise and fall process affects the seepage flow rate of the free outflow of the straw composite pipe, and the change range of the seepage rate in the depressurization process is greater than that in the pressure increase process; drying time and working pressure The water seepage of the straw composite pipe is affected interactively. Increasing the drying time can increase the water seepage of the straw composite pipe, but its water seepage stability decreases. [ABSTRACT FROM AUTHOR]

Pump inducers are usually employed within a limited flow rate range since the performance is known to drop out significantly far from their design point. Therefore, finding an optimal geometry that ensures efficient operation for a relatively wide range of flow rates is challenging. The present study tackles this problem using multi-objective optimization to identify optimal inducer configurations, delivering high performance for a wide flow range. 3D RANS single-phase turbulent simulations were performed using the k - ω turbulence model. The optimization was done by employing the Non-dominated Sorting Genetic Algorithm (NSGA-II) coupled with computational fluid dynamics (CFD). An established in-house flow optimization library (OPAL++) was used to automatically control the numerical simulations. The objective is to optimize the inducer geometrical parameters to simultaneously maximize the efficiency and pressure head curves, considering different flow rates, i.e., 80% (part-load), 100% (nominal), and 150% (overload) of the optimal flow rate for the considered pump. The optimization involves 8 most relevant design parameters, i.e., the axial blade length, blade sweep angle, blade pitch, hub taper angle, tip clearance gap, blade thickness at the hub, blade thickness at the tip, and the number of blades. A total of 5178 simulations over 37 generations have been needed to get a Pareto front containing 5 optimal configurations. This article discusses quantitatively the influence of each geometrical parameter on flow behavior and inducer performance. The results reveal in general that blade length, blade sweep angle, tip clearance gap, and blade thickness should be kept low for the considered application; inducers with high hub taper angles and 3 blades lead to optimal performance. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental 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.)

To determine the water management model of high-quality and high-yield green pepper under moistube irrigation conditions, a field planting experiment was conducted to study the individual and coupling effects of buried depth and pressure head on the growth of green pepper and efficiency of water usage. The suitable pressure head and tube depth of green pepper were determined through principal component comprehensive evaluation method. Results showed that the growth rate of stem thickness and plant height, yield, and water usage efficiency under different buried depths follow this sequence: D20>D15>D10. The growth rate of stem thickness and plant height with different pressure heads can be arranged as follows: H200>H 150>H100. The water usage efficiency can be arranged as follows: H100>H150>H200. The yield with different pressure heads can be in this order: H150>H200>H100. The coupling effect of the buried depth and pressure head significantly affected the growth rates of stem thickness and plant height (p<0.05) and water usage efficiency (p<0.01) but demonstrated no significant effect on the green pepper yield. Through the multi-indicator integrated principal component analysis method, the two main components of growth and water usage factors were extracted, and the cumulative variance contribution rate reached 93.41%. Under moistube irrigation conditions, the suitable pressure head and buried depth for green pepper were determined to be 200 and 15 cm, respectively. [ABSTRACT FROM AUTHOR]

The study is focused on numerical simulation of the infiltration process of polluted water originating from a wadi into the unsaturated soil of a bay. This study addresses the linkage between unsaturated zone and groundwater and it discusses the ability of the unsaturated soil to receive the water dried at once by the wadi and the bay. The simulation requires a number of trials, something that is experimentally expensive and sometimes impossible. The infiltration process is governed by the Richard's equation. To solve this later, the knowledge of soil water properties such as pressure head, water content and hydraulic conductivity is needed. Hence, the water retention and unsaturated hydraulic conductivity curves near saturation have been established for a range of water content going from h = (− 25 m; 25 m) to h = (− 175 m; 175 m). These curves are obtained using the simulating computer program Hydrus 2D/3D. Numerical results have been calibrated with the Musy and Soutter (Physique du sol (soil physics), Université de Technologie Compiègne, Lausanne, 1991) type relationships. It has been explained that the infiltration process from the saturated zones to the unsaturated zone is relatively slow depending on the soil structure. [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.)

Moistube irrigation is a new water-saving technology. In order to explore the effect of pressure head and soil bulk density on water infiltration of moistube irrigation in vertical inserting mode, a series of indoor infiltration experiments were performed. Three pressure heads (H1:1.0 m, H2:1.5 m and H3:2.0 m) and three soil bulk densities (D1:1.00 g·cm-3, D2:1.15 g·cm-3 and D3:1.30 g·cm-3) were set, with a total of 9 treatments, each processing 3 replicates. Wetting body was selected as observation object to record the change of wetting front profile. During the infiltration process, the Mariotte bottle was recorded and the wetting front at each time point was depicted on the side of the soil box. After 124 h of infiltration, the contours of wetting front at each time point depicted on the side of the soil box were copied onto the checkerboard to calculate the soil wetting volume, and the cumulative infiltration was calculated according to the Mariotte bottle scale and inner diameter. Studying the relationship between wetting volume, infiltration rate and cumulative infiltration with infiltration time, and the impacts of pressure head and soil bulk density on infiltration coefficient K and infiltration index α. The results showed that the pressure head and soil bulk density had significant effects on the infiltration capacity of moistube irrigation. Compared with D1, steady infiltration rates and cumulative infiltration of moistube irrigation decreased by 14.27%-33.61% and 12.92%-30.54% with the increase of soil bulk density. Compared with H1, steady infiltration rate and cumulative infiltration of moistube irrigation increased by 17.12%-37.02% and 18.67%-40.31% with the increase of pressure head. The wetted soil volume decreased with the increase of soil bulk density, while increased with the increase of pressure head. The changing process of cumulative infiltration with time was accorded with Kostiakov model. The infiltration coefficient K was positively correlated with pressure head and negatively correlated with soil bulk density, while the infiltration index α was negatively correlated with pressure head and positively correlated with the soil bulk density. Regression analysis showed that the influence of pressure head on infiltration index α was greater than soil bulk density, and the influence of pressure head on infiltration coefficient K was less than soil bulk density. The water infiltration capacity of moistube irrigation increased with the increase of pressure head, while decreased with the increase of soil bulk density. The results can provide a scientific basis for the practical application of moistube irrigation in agriculture. [ABSTRACT FROM AUTHOR]

Perforated pipes are widely used in applications such as drainage, irrigation and ventilation. The variation in the pressure head, h, in a perforated pipe follows a certain pattern. By analyzing h variation patterns at the tail ends of perforated pipes on flat slope, and the characteristic coefficient of the perforated pipe was proposed. According to the value of characteristic coefficient of the perforated pipe, perforated pipes are classified into three types, namely, short, medium and long pipes. In addition, a method for determining the type of perforated pipe based on its characteristic coefficient and length-to-diameter ratio is provided. Furthermore, on the condition of long perforated pipe, based on the locations of the maximum and minimum h values, the slope at which the perforated pipe is laid and the head loss ratio along the length of the perforated pipe, h curves are classified into five types. The experimental results demonstrate that the experimental data exhibit a variation pattern consistent with that of the calculation results, indicating that the classification of pressure head curves is, to a certain degree, reasonable and applicable. [ABSTRACT FROM AUTHOR]

A correct quantification of mass and energy exchange processes among Earth's land surface, groundwater, and atmosphere requires an accurate parameterization of soil hydraulic properties. Pedotransfer functions (PTFs) are useful in this regard because they estimate these otherwise difficult to obtain characteristics using texture and other ubiquitous soil data. Most PTFs estimate parameters of empirical hydraulic functions with modest accuracy. In a continued pursuit of improving global‐scale PTF estimates, we evaluated whether improvements can be obtained when estimating parameters of hydraulic functions that make physically based assumptions. To this end, we developed a PTF that estimates the parameters of the Kosugi retention and hydraulic conductivity functions (Kosugi, 1994, https://doi.org/10.1029/93WR02931, 1996, https://doi.org/10.1029/96WR01776), which explicitly assume a lognormal pore size distribution and apply the Young‐Laplace equation to derive a corresponding pressure head distribution. Using a previously developed combination of machine learning and bootstrapping, the developed five hierarchical PTFs allow for estimates under practical data‐poor to data‐rich conditions. Using an independent global data set containing nearly 50,000 samples (118,000 retention points), we demonstrated that the new Kosugi‐based PTFs outperformed two van Genuchten‐based PTFs calibrated on the same data. The new PTFs were applied to a 1 × 1 km2 global map of texture and bulk density, thus producing maps of the parameters, field capacity, wilting point, plant available water, and associated uncertainties. Soil hydraulic parameters exhibit a much larger variability in the Northern Hemisphere than in the Southern Hemisphere, which is likely due to the geographical distribution of climate zones that affect weathering and sedimentation processes. Key Points: We developed a set of hierarchical pedotransfer functions for the semiphysical Kosugi water retention modelAn evaluation using globally representative data demonstrated that the PTFs outperformed PTFs based on the van Genuchten retention modelGlobal maps of hydraulic parameters, derived quantities, and associated uncertainties were produced at 1‐km resolution [ABSTRACT FROM AUTHOR]

The aim of the present study is to evaluate the technical and economic feasibility of supplying recharge points for Electric Vehicles converting water pressure in excess into electric energy from a water distribution network. A real water distribution network was analyzed, by designing a power station consisting of three components: a Pump-as-Turbine, an ad hoc generator, and a control system. The last one controls the flow rate trend at the inlet of the Pump-as-Turbine to regulate the rotational speed corresponding to the optimal range of efficiency. Energy produced permits to supply a recharging point for Electric Vehicles on site with the aim to convert water pressure generally dissipated and, consequently, lost into a renewable energy and to reduce power grid congestion. The economic analysis confirms the convenience of the proposed power station, and overall, a comparable cost with pressure reduction valve devices normally adopted to control pressure pattern and leakages of a water distribution network. [ABSTRACT FROM AUTHOR]

The Crest of an Ogee spillway with a curved plan is longer than that of one with a straight crest; therefore, its capacity for the overflow at any reservoir level is higher than that of the straight-crested spillway. Thus it is a preferred design in most water ponding projects. The objective of this study was to investigate the degree of its curvature on its hydraulics. This was a achieved on a 1:25 experimental model of the Germ chai ogee spillway at the Hydraulics Laboratory of the Soil Conservation and Water Management Research Institute of the Ministry of Jihadi Agriculture. The results revealed that the cavitation number at any discharge rate was higher than the critical value compared with that of the straight- crested weirs Moreover, the discharge coefficient was lower than that of the other type with an equal crest length.

The unsaturated hydraulic conductivity K(h) is a key soil parameter governing the water and solute transportation processes. The course of this function depends on the geometry of the pores which is determined by the soil's physical and chemical properties. Many studies focus on the comparison of soil hydraulic conductivity under different conditions. Despite the recent progress in this research field, no reference method for measuring the K(h) in situ exists. This study focuses on the effect of the initial water content of the soil as a factor influencing the measured K(h). The study was performed in situ over short time period and with several replications close to each other in order to reduce the effect of other factors which could cause variations. Two tension infiltrometers were used and compared: A Hood infiltrometer IL-2700 and a Minidisk infiltrometer. Three different levels of initial water content (dry, medium wet and wet) were applied for each of the two infiltrometers, and three pressure heads (-0.5; -1 and -3 cm) for each measurement. According to the results, the Minidisk infiltrometer showed significant sensitivity to the initial water content, while measurements performed using the Hood infiltrometer were more stable.

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A dual-technique-based inline strategy was investigated in this study as a sustainment to conventional-technique skills in terms of limitation of wave oscillation period spread-out. Instead of the single polymeric short section employed by the latter technique, the former is based on replacing an up- and downstream short section of the primitive piping system using another couple made of polymeric pipe-wall material. Numerical computations used the method of characteristics for the discretization of unconventional water-hammer model based on the Vitkovsky and the Kelvin-Voigt formulations. The efficiency of the dual technique was considered for two operating conditions associated with up- and downsurge frames. Moreover, two pipe-wall material types were utilized for short-section pipe wall, namely the HDPE or LDPE materials. Additionally, the conventional technique was also addressed in this study, for comparison purposes. First, analyses of pressure-head, circumferential-stress and radial-strain wave patterns, along with wave oscillation periods examination, confirmed that the dual technique could improve the efficiency of the conventional one, providing acceptable trade-off between the attenuation of pressure-head and circumferential-stress peaks (or crests), and limitation of period spreading and radial-strain amplification. Second, a parametric study of the sensitivity of the wave damping to the employed short-section dimensions was performed in terms of short-section length and diameter. This parametric study helped estimate the near-optimal values of the short-section dimensions. [ABSTRACT FROM AUTHOR]

Hydraulic resistance is one of the most important factors which affect the velocity of the partially submerged landslide when it moves into river at a high speed. In this paper, an experiment system was designed including a water tank, a moving frame fixed over the tank with liquid level sensors, blocks, and velocity control apparatus. Six blocks with different areas were used for experiments and each block moved at five different velocities in water tank. Test results showed that the increment of the pressure head was proportional to the square velocity of submerged block. Based on that, the total water pressure and corresponding hydraulic resistance of the moving block in water tank were obtained, and the latter was used to analyze hydraulic resistance acting on partially submerged landslide. Method of slice was applied to calculate the forces of landslide with curved slip surface. The dynamics and kinematics equation of landslide were used to calculate the velocity. Taking the Dayantang landslide as an example, velocities with different travel distance were obtained. The results showed that the maximum velocity of Dayantang landslide considering hydraulic resistance was 18.6% less than that without considering hydraulic resistance.

It is typically stated that the Pacific-to-Arctic oceanic flow through the Bering Strait (important for Arctic heat, freshwater, and nutrient budgets) is driven by local wind and a (poorly defined) far-field 'pressure head' forcing, related to sea surface height differences between the Pacific and the Arctic. Using monthly, Arctic-wide, ocean bottom pressure satellite data and in situ mooring data from the Bering Strait from 2002 to 2016, we discover the spatial structure of this pressure head forcing, finding that the Bering Strait throughflow variability is dominantly driven from the Arctic, specifically by sea level change in the East Siberian Sea (ESS), in turn related to westward winds along the Arctic coasts. In the (comparatively calm) summer, this explains approximately two thirds of the Bering Strait variability. In winter, local wind variability dominates the total flow, but the pressure head term, while still correlated with the ESS-dominated sea level pattern, is now more strongly related to Bering Sea Shelf sea level variability. [ABSTRACT FROM AUTHOR]

Many watershed studies rely on pressure transducers to measure and report stream and groundwater levels in order to characterize the hydrology of the region. The accuracy of pressure transducers in some applications have recently been questioned in studies reporting artificially exaggerated high or low pressure readings that cannot be explained by daily hydrological fluctuations. In a watershed field investigation, data analyses have revealed, for some sensors, patterns of artificial changes in stream and groundwater levels as a function of water and atmospheric temperature. These patterns do not follow the expected variation that could be caused by natural phenomena (i.e. changes in head caused by evapotranspiration). Laboratory analyses of temperature-induced artificial pressure changes reproduces this error and yielded functional relationships for thermal artifact corrections. Using these relationships, stream and groundwater levels can be back-calculated yielding a more accurate watershed hydrologic characterization. By removing the thermal artifacts from laboratory and field data, errors are reduced by up to 65% (laboratory) and 81% (field data). The developed procedure can be used in other settings where pressure transducers are used, such as studies in rainfall/runoff variations, runoff measurements in urban settings, and the impacts of new development in rural watersheds. [ABSTRACT FROM AUTHOR]

Subsurface irrigation is a type of water-saving technology. However, poor anti-clogging abilities and large energy consuming of the existing subsurface irrigation emitters present a significant obstacle to the development of subsurface irrigation. Aimed to this problem, a new type of subsurface irrigation emitter, vertical tube emitter, was proposed. This study investigated the effects of pressure head, vertical tube diameter, initial moisture content, and soil bulk density and infiltration time on infiltration characteristics of soil moisture under irrigation system with vertical tube emitter. Laboratory experiments were carried out in State Key Laboratory Base of Eco-hydraulic Engineering in Arid Area in silt loam. The experiment was conducted using an orthogonal design method including 9 treatments and one control test. In the experiment, the pressure head was designed with different levels of 0.6, 1.3 and 2.0 m, the vertical tube diameter was 4, 8 and 12 mm, initial moisture content was 7%, 10% and 13% and soil bulk density was 1.32, 1.37 and 1.42 g/cm3. During the experiment, the cumulative infiltration was measured by difference of water levels in Markov bottle. The water level was recorded every 1, 2, 5, and 10 min in the first 100 min, every 20 min from 100 to 180 min, and every 30 min from 180 to 300 min, and every 60 min from 300 to 420 min. The empirical equation was established between cumulative infiltration and influence factors. The first derivative of the equation with respect to time was considered as the infiltration rate empirical equation. Then the partial deviation of the equation with respect to each factor could reflect sensitivity of infiltration rate to each factor. Based on the curves of influence factors and cumulative infiltration, an empirical model was established to estimate cumulative infiltration. The model had the determination coefficient of 0.96 and the measured and estimated values were correlated with correlation coefficient 0.98 (P<0.01). The model was validated with measured values of control test. The validation revealed R2 higher than 0.99 and the root mean square error from 0.1125 to 0.1353 L, indicating that the established model was good at cumulative infiltration estimation under irrigation system with vertical tube emitter. The effect of pressure head, vertical tube diameter and infiltration time on cumulative infiltration was the largest among all the factors. The infiltration rate decreased greatly during the first 2 h of experiment then stabilized after 5-6 h. The stable infiltration rate was 0.08-0.25 L/h when the pressure head was 0.6-2.0 m, vertical tube diameter was 4-12 mm, initial moisture content was 7%-13 % and soil bulk density was 1.32-1.42 g/cm3 during 7 h. The sensitivity analysis results showed that pressure head was the main factor affecting the infiltration rate, followed by vertical tube diameter, soil bulk density and initial soil moisture content. The infiltration rate had a positive correlation with pressure head and vertical tube diameter, however, had a negative correlation with initial moisture content and soil bulk density. And the rate of change of infiltration rate reduced gradually for all the influence factors. In the future, depth of vertical tube emitter and muddy water infiltration should be considered in studying the infiltration characteristics of soil moisture in the irrigation system with vertical tube emitter, and filed experiments should be combined with pipe network system to study the practical application effects of vertical tube emitter. [ABSTRACT FROM AUTHOR]

The understanding of the structure of the spatial variability of soil surface hydraulic properties on steep slopes is important for modeling infiltration and runoff processes. The objective of this study was to investigate the spatial variability of these properties on a steep slope of the Loess Plateau in northwest China. A 9600 m² area was systematically sampled in a grid of 106 points spaced 10 m x 10 m. Hydraulic properties were determined with a disc infiltrometer under multiple pressure heads (-15, -9, -6, -3, 0 cm) at each sample point. Classical and geo-statistical methods were used for data analysis. The results indicated that the variation of Gardner's a and hydraulic conductivities at all applied pressure heads was moderate and the heterogeneity for hydraulic conductivities increased as the applied pressure head increased. Along the slope, hydraulic conductivities generally decreased downwards, while the Gardner's a fluctuated slightly. The Gardner's a of the shaded aspect of the slope was greater than that of the sunny aspect. The hydraulic conductivities of the shaded aspect were greater at higher pressure heads as compared to the sunny aspect, but lower than those of the sunny aspect at lower pressure heads. Correlation analysis showed a negative correlation between hydraulic conductivity and soil organic matter and clay (A compreensão da estrutura da variabilidade especial das propriedades hidráulicas do solo de encostas íngremes é importante na modelagem dos processos de infiltração e de escoamento superficial da água. O objetivo deste estudo foi investigar a variabilidade destas propriedades em uma encosta íngreme do "Loess Plateau" do noroeste da China. Uma área de 9600 m² foi sistematicamente amostrada em um grid de 106 pontos espaçados de 10 m x 10 m. As propriedades hídricas foram determinadas com um infiltrômetro de disco operando sob múltiplas cargas hidráulicas (-15, -9, -6, -3, 0 cm) em cada ponto de observação. Métodos clássicos e geoestatísticos foram empregados na análise dos dados. Os resultados mostraram que a variação do índice a de Gardner e das condutividades hidráulicas em todas as cargas aplicadas foi moderada e que a heterogeneidade das condutividades hidráulicas aumentou à medida que a carga hidráulica aumentava. Na direção do declive, as condutividades geralmente decresceram a jusante, enquanto os a de Gardner flutuavam moderadamente. Os a de Gardner das encostas sombreadas foram maiores do que os das encostas ensolaradas. As condutividades hidráulicas das encostas sombreadas foram maiores para cargas hidráulicas maiores em comparação com as encostas ensolaradas, mas menores que as das encostas ensolaradas para cargas hidráulicas menores. A análise de correlação mostrou uma correlação negativa entre a condutividade hidráulica e os teores de matéria orgânica e argila (

Flow recirculation is an unpleasant and even hazardous phenomenon that can cause mechanical damage in turbomachinery and has to be prevented during their operations. We numerically studied the effects of return channel blade curvature on reducing the recirculation of flow inside the return channel vanes of a multi-stage centrifugal pump. Computational fluid dynamics (CFD) analyses were performed for a wide range of volumetric flow rates. The standard k-ε turbulence model was adopted as the turbulence model, and the impeller rotation simulated employing the Multiple reference frames (MRF) method. First, a baseline model together with five different modified geometries for return channel was studied and compared using a two-stage pump framework. The results reveal that decreasing the curvature of the return channel blade makes smooth streamlines and eliminates the flow recirculation inside the return channels. As the second part, two return channels with the highest pump performance were selected to be used in the simulation of a multistage pump. The simulations of the multi-stage pump show that the flow inside the baseline return channel includes considerable areas of flow recirculation, while the modified return channels again have attached flow stream. It is concluded that the return channels with the smooth curvatures and outlet blade angles above 90° remove the flow recirculation inside the return channels, resulting in higher pump efficiencies. [ABSTRACT FROM AUTHOR]

Introduction: Estimating groundwater inflow into a tunnel before and during the excavation process is an important task to ensure the safety and schedule during the underground construction process. Case description: Here we report a case of the forecasting and prevention of water inrush at the Jinping II Hydropower Station diversion tunnel groups during the excavation process. The diversion tunnel groups are located in mountains and valleys, and with high water pressure head. Three forecasting methods are used to predict the total water inflow of the #2 diversion tunnel. Furthermore, based on the accurate estimation of the water inrush around the tunnel working area, a theoretical method is presented to forecast the water inflow at the working area during the excavation process. Discussion and evaluation: The simulated results show that the total water flow is 1586.9, 1309.4 and 2070.2 m/h using the Qshima method, Kostyakov method and Ochiai method, respectively. The Qshima method is the best one because it most closely matches the monitoring result. According to the huge water inflow into the #2 diversion tunnel, reasonable drainage measures are arranged to prevent the potential disaster of water inrush. The groundwater pressure head can be determined using the water flow velocity from the advancing holes; then, the groundwater pressure head can be used to predict the possible water inflow. The simulated results show that the groundwater pressure head and water inflow re stable and relatively small around the region of the intact rock mass, but there is a sudden change around the fault region with a large water inflow and groundwater pressure head. Different countermeasures are adopted to prevent water inrush disasters during the tunnel excavation process. Conclusion: Reasonable forecasting the characteristic parameters of water inrush is very useful for the formation of prevention and mitigation schemes during the tunnel excavation process. [ABSTRACT FROM AUTHOR]

Summary The impact of bedrock groundwater seepage on surface hydrological processes in a foot slope area is an important issue in hillslope hydrology. However, properties of water flux vectors around a seepage area are poorly understood because previous studies have lacked sufficient spatial resolution to capture detailed water movements. Here, we conducted hydrometric observations using unprecedented high-resolution and three-dimensional tensiometer nests in the mountainous foot slope area of the Hirudani experimental basin (Japan). Our findings are summarized as follows: (1) a considerable quantity of groundwater seeped from the bedrock surface in the study site. A groundwater exfiltration flux occurred constantly from a seepage area regardless of rainfall conditions. Saturated lateral flow over the bedrock surface occurred constantly in the region downslope of the seepage area. Groundwater was likely to mixed with soil water infiltration and flowed toward the lower end of the slope. (2) During the wet season, the seepage area expanded ∼3 m in the upslope direction along the bedrock valley in a single season. (3) The pressure head waveform observed in the seepage area showed gradual and significant increases after large rainfall events. However, the seepage pressure propagated within a relatively narrow area: a slope distance of ∼4 m from the seepage point in the downslope direction due to the damping of seepage pressure. (4) Within the whole study area, groundwater seeped from a narrow area located at the bottom of the valley line of the bedrock surface. The shape of the seepage area changed along the valley line in the wet season. Overall, we reveal spatial and temporal variations in bedrock groundwater seepage under the soil mantle and the effects on soil water fluxes. These findings should improve the accuracy of models for predicting surface hydrogeomorphological processes in mountainous hillslopes. [ABSTRACT FROM AUTHOR]

Improving the maneuverability of ships by increasing the tractional force of the thrusters is considered. To minimize the losses associated with swirling liquid flow and the variable attack angles in reversing, the traditional configuration must be modified, and the inclination of the thruster blades must be optimized. To increase the efficiency, the rotors should have different speeds and blade inclinations. [ABSTRACT FROM AUTHOR]

Groundwater ridging is the rapid rise of a shallow water table during a rainfall event, in an environment where, in the pre-event period, the capillary fringe extends to the ground surface. Groundwater ridging is widely cited to account for the observed significant appearance of pre-event water in a stream stormflow hydrograph. Various hypotheses have been advanced to explain the groundwater-ridging mechanism; and most recently, from a field study site in South Africa, an energy hypothesis was proposed, which explains that groundwater-ridging water-table rise is a result of rapid introduction and transmission of additional pressure head into the capillary fringe from an intense rainfall at the ground surface. However, there is a need for further analysis and evidence from other field study sites to confirm and support this newly proposed energy hypothesis. The objectives of this paper are, therefore, as follows: to review previous observations on groundwater ridging, from other study sites, in order to deduce evidence of the newly proposed energy hypothesis; to present and evaluate a one-dimensional diffusion mathematical model that can simulate groundwater-ridging water-table rise, based on the newly proposed energy hypothesis; and to evaluate the importance of a capillary fringe in streamflow generation. Analysis of previous observations from other study sites generally indicated that the rate of groundwater-ridging water-table rise is directly related to the rainfall intensity, hence confirming and agreeing with the newly proposed energy hypothesis. Additionally, theoretical results by the mathematical model agreed fairly well with the field results observed under natural rainfall, confirming that the rapidly rainfall-induced energy is diffusively transmitted downwards through pore water, elevating the pressure head at every depth. The results in this study also support the concept of a three-end-member stream stormflow hydrograph and contribute to the explanation of how catchments can store water for long periods but then release it rapidly during storm events. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Artificial recharge to groundwater is steadily assuming importance in the wake of the decline in water level in several parts of the country. Recharge through an injection well is the most suitable option of artificial recharge for semi-confined and confined aquifers, especially in urban and industrial areas as it requires little space. Recharging capacity of a well is an important criterion in deciding the number of recharge structures required for large-scale planning of artificial recharge. The present work focuses on determining the recharging capacity of a well in a semi-confined alluvial aquifer in the middle Ganga Plain, wherein it has been found that the actual recharging capacity is lesser than the product of the well-specific capacity and available pressure head. [ABSTRACT FROM AUTHOR]

Xylem resistance to water stress-induced cavitation is an important trait that is associated with drought tolerance of plants. The level of xylem cavitation experienced by a plant is often assessed as the percentage loss in conductivity ( PLC) at different water potentials. Such measurements are constructed with samples that are excised underwater at native tensions. However, a recent study concluded that cutting conduits under significant tension induced cavitation, even when samples were held underwater during cutting. This resulted in artificially increased PLC because of what we have termed a 'tension-cutting artefact'. We tested the hypothesized tension-cutting artefact on five species by measuring PLC at native tension compared with after xylem tensions had been relaxed. Our results did not support the tension-cutting artefact hypothesis, as no differences were observed between native and relaxed samples in four of five species. In a fifth species ( L aurus nobilis), differences between native and relaxed samples appear to be due to vessel refilling rather than a tension-cutting effect. We avoided the tension-cutting artefact by cutting samples to slightly longer than their measurement length and subsequent trimming of at least 0.5 cm of sample ends prior to measurement. [ABSTRACT FROM AUTHOR]

In order to assess subfoliar sprinkler irrigation quality, the hydraulic evaluation of the sprinkler irrigation system in banana farm was carried out at three different pressures in five modules of the system. The evaluated indicators were: pressures to the beginning and final of the lateral, flows in those same points, coefficient of uniformity of Christiansen, distribution uniformity and area irrigated appropriately. The results show that the variation of the pressure surpass 20%, while in the flows it overcomes 10%. It was proven that high coefficients of uniformity do not mean the biggest area irrigated appropriately. The three pressures of work evaluated guarantee high coefficients of uniformity, however, if what is wanted is to reach the biggest appropriately irrigated area it should be worked to 310,26 kPa. [ABSTRACT FROM AUTHOR]

With the introduction of intelligent heuristic optimization strategies, there has been an increasing interest in the use of these methods for solving the design problem of water distribution networks (WDN). This paper proposes the use of a new version of heuristic shuffled frog leaping (SFL) algorithm for solving the problem of WDN design. First, in order to speed up the original SFL algorithm, an adaptive parameter is introduced. Then, momentum parts are added to the SFL to increase the ability of the algorithm in escaping from local optimums. Finally, a mutation operator is proposed to increase the diversification property of the algorithm. The new version of the SFL algorithm is called adaptive mutated momentum shuffled frog leaping (AMMSFL). The proposed AMMSFL is then applied to solve WDN design problems. An illustrative and comparative illustrative example is presented to show the efficiency and superiority of the introduced AMMSFL compared to the other well-known heuristic algorithms. [ABSTRACT FROM AUTHOR]

This article describes an effective procedure for reducing the water content of excess sludge production from a wastewater treatment plant by increasing its concentration and, as a consequence, minimizing the volume of sludge to be managed. It consists of a pre-dewatering sludge process, which is used as a preliminary step or alternative to the thickening. It is made up of two discontinuous sequential stages: the first is resettling and the second, filtration through a porous medium. The process is strictly physical, without any chemical additives or electromechanical equipment intervening. The experiment was carried out in a pilot-scale system, consisting of a column of sedimentation that incorporates a filter medium. Different sludge heights were tested over the filter to verify the influence of hydrostatic pressure on the various final concentrations of each stage. The results show that the initial sludge concentration may increase by more than 570% by the end of the process with the final volume of sludge being reduced in similar proportions and hydrostatic pressure having a limited effect on this final concentration. Moreover, the value of the hydrostatic pressure at which critical specific cake resistance is reached is established. [ABSTRACT FROM PUBLISHER]

Marine reactors are received increasing attention recently in the field of ocean engineering. The effect of platform motion on the coolant flow of an offshore nuclear power plants is very complicated, which is required further analysis. In this paper, effects of rolling motion on single-phase flow fluctuation with different loops were investigated experimentally. And a mathematical model was also developed to study the mechanism of the influence of rolling motion on flow fluctuation with different pressure head, rolling parameters and layouts of flow loops. For the closed loop, the flow rate was adjusted by two ways, i.e. regulating the pump rotation speed and changing the state of regulating valve. While for the opened loop, the pressure head was always supplied by elevated water tank. The Reynolds number ranged from 300 to 8000, and ranges of the rolling period and amplitude were 8–20s and 10–30°, respectively. The results show that increase of the loop resistance and pressure head results in smaller flow fluctuation amplitudes. Effects of rolling motion on single-phase flow fluctuation weaken as the oscillatory pressure drop decreases or the pressure head increases. If the pressure head is high enough, the effect of rolling motion on flow fluctuation could be neglected. Rolling motions influence the flow fluctuation behaviors in different ways for the opened loop and the closed loop, due to the inequable oscillatory pressure drop. The flow fluctuation model shows a good agreement with the experiments and the analyzing method is expected to other oscillating flow system. [ABSTRACT FROM AUTHOR]