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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]

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.

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]

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]

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.

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 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]

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.

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.

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]

The characteristics of a multistage electrohydrodynamic converter (EHDC) have been studied, and the results are presented in this paper. The diagram of an experimental installation is described; the pressure head, flow rate, and current characteristics are provided as a function of time and the EHDC supply voltage. The factors determining the EHDC parameters and the methods of their regeneration are determined. [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.