Flow Division Research Articles

Sedimentary processes and patterns in deposits corresponding to freshwater lake-facies of hyperpycnal flow – An experimental study based on flume depositional simulations

Abstract The article establishes a depositional model for lacustrine hyperpycnal flow by examining dynamics, transport factors, and laminae formation. The results show that several typical experimental phenomena such as fluid front mixing, double flow division, underwater leap, water skiing, and “new head” can be observed in the flume experiment. Based on the experimental observation of the flow process, three modes of transport of hyperpycnal flow in freshwater lake basins are summarized: bottom-bed loading, suspended loading, and uplift loading. Further, the change of fluid properties in hyperpycnal flow is summarized in three stages: a high-concentration stage, a low-concentration stage, and an uplifting stage. There are two main factors affecting the long-range transport of hyperpycnal flow: (1) the concentration difference between the head deposits and the ambient water body and (2) shear force of turbulence in the upper part of hyperpycnal flow. The simulation experiments of hyperpycnites laminae show that the laminae change from continuous to intermittent with the increase of the transportation distance. It is clear that the mode of transport of the hyperpycnal flow has a controlling effect on the degree of development of the laminae. Eventually, a depositional model of lake-facies hyperpycnal flow under experimental conditions was constructed.

Continuously Variable Two-Flow Hydrostatic-Mechanical Transmission of Crawler Tractor

The paper proposes an original design of a continuously variable two-flow hydrostatic-mechanical transmission, which ensures division of the power flow along the sides of the crawler tractor. To ensure stability of rectilinear motion, their volumetric and mechanical efficiency, the maximum pressure of the working fluid in the hydraulic transmission, the maximum speed and torque on the shaft of the hydraulic motor. The parameters of an unregulated hydraulic motor, an adjust-table pump and mechanical transmission elements are selected. A mathematical model of the rectilinear motion of a caterpillar tractor with a continuously variable hydrostatic-mechanical transmission has been developed, taking into account the weight of the tractor, the parameters of the running system, the characteristics of the internal combustion engine, the parameters and efficiency of hydraulic machines, gearboxes, range and transfer boxes, planetary gear and allowing to determine the efficiency of individual branches and the entire transmission, carry out traction calculations of the tractor. A calculation program has been developed that implements the mathematical model. The parameters of the dual-flow transmission are selected so that most of the torque is transmitted through the mechanical branch and the transmission has a fairly high efficiency value. The maximum value of tractor traction efficiency is realized in the second and third ranges, which are designed to perform basic tillage operations.

Experimental and numerical pressure drop investigation of a protruding tube microchannel heat exchanger

An experimental and numerical fluid flow study in a micro heat exchanger (microHEX) is conducted in this work to investigate its pressure drop characteristics. The microHEX sample presents a high degree of protrusion of the microchannels inside the inlet and outlet manifolds (Lprot /Dm =0.7), a large manifold-to-branch area aspect ratio (Am/As =37), and a very small flow division in each microchannel (β=1/34). These features configure T-junctions that differ completely from the conventional ones in the literature. Experimental measurements of the microHEX pressure drop were performed for the Reynolds range of 300-2200. The numerical methodology combines a 1D model to evaluate the pressure drop of a single microchannel, adding minor entrance and exit losses due to the change of section and direction. A CFD numerical simulation evaluates the particular pressure loss associated with the dividing T-junction towards the protruded microchannel. The numerical simulation pressure drop results compared well with the experimental measurements, reporting a difference of 3.11% for an initial case. An extension of the work will soon cover all the collected experimental cases.

Суверенитет России на трансграничные реки

The article discusses issues of Russian sovereignty over transboundary rivers. It reveals that in accordance with the UN Charter and international treaties, states have full sovereignty over their natural resources. As to environmental protection against transboudary pollution and damage and also in relation to the use of shared natural resources, international law applies this principle in combination with the principle of limited sovereign rights. In conformity with the intergovernmental water basin agreements of Russia with the watershed countries the external involvement into the national decision-making process is carried out through mutual commitments and obligations to recover the environmental damage, conducting joint monitoring, notification about on-going and planned activities that have or may have negative impacts on a transboundary river, related water uses and facilities, division of a water flow, joint inspections and agreed exploitation of hydrotechnical objects. Application of the limited sovereign rights to shared water resources has an objective nature-based rationale – ecosystem integrity of a shared water body, that justifies and ensures its protection against degradation, equitable and reasonable utilization by coastal states.

Gas Chromatographic Determination of Residual Concentrations of a Mixture of Organochlorine Pesticides in Food Products

Purpose of research. The aim of the work is to optimize the conditions for gas chromatographic determination of a mixture of eight organochlorine pesticides: aldrin, hexachlorobenzene, heptachlor, α-hexachlorocyclohexane, γ-hexachlorocyclohexane, dichlorodiphenyltrichloromethylmethane, dichlorodiphenyldichloroethane and dichlorodiphenyldichloroethylene.Methods. For chromatographic studies of organochlorine pesticides we used a Shimadzu GC-2010Plus gas chromatograph (Shimadzu, Japan) equipped with an automatic equilibrium vapor sample dispenser NT200N, electron-capture detector based on 63Ni and quartz capillary nonpolar column "Chromatek" SPB-5 (30 m, 0.32 mm, film thickness on the basis of phenyl(5%) and dimethyl(95%) polysiloxanes 0.5 μm) with an operating temperature range of 60°C 320/340°C. The chromatograms were processed in the application LabSolutions GPC.Results. On the basis of experimentally obtained data the optimal conditions for gas chromatographic determination and separation of eight-component mixture of organochlorine pesticides were selected, namely: the value of mobile phase flow division 1:10, carrier gas flow rate – 1.0 ml/min, two-stage temperature programmable column mode from 160 to 240°C with the rate of increase of 5°C/min. The metrological characteristics of the analysis and validation of the results of the proposed technique with the method of high-performance liquid chromatography were evaluated. Good reproducibility of chromatography results with the possibility of detection of organochlorine pesticides at the level of 10-6 – 10-5 μg/cm3 was proved. Application of Fisher's test has shown absence of significant differences in reproducibility of sampled populations the investigated methods of chromatographic analysis of COPCs are equally accurate. Extraction sample preparation of samples of real objects was proposed, the calculated extraction degrees >84% allow to recommend the technique for quantitative determination of analytes.Conclusion. The method of gas chromatographic analysis was tested for determination of organochlorine pesticides in samples of drinking water and baby puree (Russia) by additive method. Exceeding the norms of residual contents of organochlorine pesticides in the samples of the food products under study was not detected.

CFD Analysis of Pulsatile Non-Newtonian Blood Flow in a Multi-Staged Stenosed Bifurcated Carotid Artery

Accumulation of plaque on the arterial walls leads to a cardiovascular condition known as Atherosclerosis. This leads to lumen stenosis, and when it occurs in the carotid artery, it can impede the blood-flow to the face, brain, and neck, potentially leading to a stroke. The aim of this paper is to provide a comprehensive study of the carotid artery under multiple stenosed conditions using Computational Fluid Dynamics. In this study, blood has been considered to be a non-Newtonian fluid exhibiting pulsatile flow based upon the Carreau model and a two-dimensional bifurcated human carotid artery has been modelled. The Navier-Stokes equations-based FVM (Finite Volume Method) is used to analyze the flow inside the artery, while RANS k-ω SST turbulence model has been applied in the analysis of parameters of blood under stenosed conditions. Four models based on different stages of stenosis (0%; 25%; 50% and 75%) have been developed with simulations run on Ansys to find the effects under stenosis. For all the simulations, 65:35 flow division has been used, indicating that 65% of the total blood flows through the Internal Carotid Artery and 35% flows through the External Carotid Artery. Velocity and pressure contour, velocity distribution on the modelled plane and wall shear stress on arterial walls are the primary parameters studied at varying timescales of a cardiac cycle. As the stenosis stage increases, the flow separation can be predicted with higher accuracy. With the help of these parameters, one can build and design better treatment choices, such as designing of stents with different materials or adding of Ag-Au (Silver - Gold) nanoparticles in the blood to change the hemodynamics.

Hydrodynamic characteristics and particle tracking of 90° lateral intakes at an inclined river slope

Lateral intakes are common in rivers. The pump efficiency and sediment deposition are determined by the local hydrodynamic characteristics and mainstream division width. The hydraulic characteristics of lateral withdrawal from inclined river slopes at different intake elevations should be investigated. Meanwhile, the division width exhibits significant vertical non-uniformity at an inclined river slope, which should be clarified. Hence, a three-dimensional (3-D) hydrodynamic and particle-tracking model was developed with the Open Source Field Operation and Manipulation (OpenFOAM), and the model was validated with physical model tests for 90° lateral withdrawal from an inclined side bank. The flow fields, withdrawal sources, and division widths were investigated with different intake bottom elevations, withdrawal discharges, and main channel velocities. This study showed that under inclined side bank conditions, water entered the intake at an oblique angle, causing significant 3-D spiral flows in the intake rather than two-dimensional closed recirculation. A lower withdrawal discharge, a lower bottom elevation of the intake, or a higher main channel velocity could further strengthen this phenomenon. The average division width and turbulent kinetic energy were smaller under inclined side bank conditions than under vertical bank conditions. With a low intake bottom elevation, a low withdrawal discharge, or a high main channel velocity, the sources of lateral withdrawal were in similar ranges near the local inclined bank in the vertical direction. Under inclined slope conditions, sediment deposition near the intake entrance could be reduced, compared to that under vertical slope conditions. The results provide hydrodynamic and sediment references for engineering designs for natural rivers with inclined terrains.

Screening of accident scenarios of hydrogen refueling stations based on HyRAM+ and Latin hypercube sampling

Due to the boom in hydrogen energy, risk assessment for hydrogen refueling station (HRS), which is as an infrastructure to supply hydrogen energy, is increasingly important. It is also crucial to screen out accident scenarios with low probabilities and low harms. This study theoretically focuses on an accident scenarios screening method for HRS based on Hydrogen Plus Other Alternative Fuels Risk Assessment Models (HyRAM+) and Latin hypercube sampling (LHS). According to the unit division of process flow in HRS, accident scenarios were preliminarily screened by accident consequence frequencies and maximum leakages. By comparing credible factor C and Potential Loss of Life (PLL), accident scenarios were screened secondly to obtain maximum credible accident scenario (MAS). The uncertainties of hydrogen leak, leak isolation, ignition possibilities, and the occupant positions were considered using LHS method for accident consequence frequencies and PLL. The assessment results for one HRS indicate that consequence frequencies of jet fire and explosion may be underestimated by HyRAM+. Moreover, MASs of jet fire and explosion were determined by complete rupture of the pipeline of the hydrogen compressor unit and explosion has a more significant impact on property loss than jet fire.

ML-Based Approach to Predict Carotid Arterial Blood Flow Dynamics

In the current study, a numerical model has been developed to simulate the blood flow characteristics in the human carotid artery. The data thus generated is analyzed to understand the blood flow variations and predict the flow characteristics using Machine Learning techniques. In developing the numerical model, the key features of the system, namely, the blood, is modeled as an incompressible Newtonian fluid, and the artery is an elastic pipe. This model is simulated using COMSOL software by varying the material properties of the artery. Univariate analysis was performed to gain insight into the features' behaviour and target variables. Subsequently, machine-learning regression models were trained using the data generated from the idealized human carotid artery. Furthermore, the validity of the data was ensured by comparing it with flow division ratios available in the literature. The evaluation of these models was conducted by calculating the Mean Absolute Error values for the test dataset, resulting in the following values: polynomial regressor (0.0106), hyper-tuned support vector regressor (0.0487), decision tree regressor (0.000), random forest regressor (0.0156), Adaboost (0.0508), gradient-boosting (0.0044), and XGboost (0.0043). A quantile loss function was employed to assess the prediction uncertainty. According to the theory of loss function, models with low loss values are considered good predictors. The prediction uncertainty was measured by applying quantile loss function, and it identified that the random forest regressor as the best predictor model for the data, followed by the polynomial regression of degree 3. Prediction intervals for the target variable were computed by leveraging the random forest quantile regressor model. Moreover, the developed polynomial model was utilized to investigate the presence of stenosis in the artery.

Fuzzy Control Strategy of Tunnel Lighting Based on Input Parameter Optimization

The mismatch between illumination and traffic safety brightness in tunnels leads to much-wasted lighting energy and safety problems. Effective control of tunnel lighting can be achieved by lighting on demand and reducing lighting energy consumption. This paper uses the curve fitting and linear interpolation methods to optimize the luminance reduction factor K proposed in the Highway Tunnel Lighting Rules. It constructs a multi-zone division of traffic speed, traffic flow, and brightness outside the tunnel to obtain the K value under actual road conditions and to establish a fuzzy controller for dimming control. The simulation demonstrates that the proposed strategy can save about 37.38% of tunnel lighting compared to the graded lighting control strategy.

AFD-Former: A Hybrid Transformer With Asymmetric Flow Division for Synthesized View Quality Enhancement

Recently, CNN-based post-processing has shown great potential in Synthesized View Quality Enhancement (SVQE). However, due to the limited receptive field of convolution, it is ineffective in explicitly modeling long-range dependencies, which are critical to eliminate the distortion induced by Depth Image Based Rendering (DIBR) in synthesized views. Although transformers exhibit tremendous success at learning global contextual information, it is weak at extracting local texture information. To take full advantages of the CNN and transformer, we present a novel U-shaped hybrid transformer with asymmetric flow division to collaboratively capture global-local information for SVQE, termed as AFD-former. Specifically, the AFD-former utilizes the Transformer-CNN Block (TCB) as encoder and decoder, in which several Dynamic Hybrid Attention Blocks (DHABs) are designed to simultaneously model long-range interactions and retain texture details. Then, considering that the deeper layers of the U-shaped network play more roles in capturing global information while shallow layers more in extracting local information, an Asymmetric Flow Division Unit (AFDU) is embedded into each DHAB to assign different contributions of global-local contextual information to the transformer and CNN branches across different layers. Finally, a dynamic learnable modulator is incorporated into two branches to help model effectively feature representation learning. That can be viewed as the dynamic process of adjusting the weight for each channel of the input feature based on contextual cues. Extensive experiments demonstrate that the proposed AFD-former can significantly enhance perceptual quality of synthesized views with similar SVQE speed compared with the related state-of-the-art SVQE methods. The source code will be available at https://github.com/House-yuyu/AFD-former.

Tidal impacts on the discharge division and freshwater transport in the Berau Delta, East Kalimantan, Indonesia

Flow division at bifurcations is important in controlling material carried from the terrestrial to the coastal zone in tidally influenced deltas. The present study aims to identify the impacts of tides on flow division and freshwater transport in the Berau Delta, East Kalimantan. The Princeton Ocean Model (POM) is applied to simulate the hydrodynamics with forcing from river discharges and tides. Tides at open seas and observed river discharge at upstream locations were used to set model boundaries. Model validation was accomplished by comparing measurements of tidal elevation and salinity time series with model results. The model results reproduce the observed in temporal variations of tidal elevation and salinity. Model results highlight that the tidal amplitude has large influence on discharge division at the tidal junction. Tides enhance equal subtidal flow distribution in the river junctions, with the influence of tide is 15% on subtidal flow distribution in the bifurcations. Freshwater discharge at the Berau Delta flows mainly to the north and middle outlet with 90% of the total discharge. Based on an analysis model results, the decomposition of freshwater transport reveals that advection and tidal pumping are major factor, which are fluctuate in fortnight cycle.

Experimental and numerical investigations of particle suspension suppression mechanisms for a particle-suppression device in a stirred liquid bath

Particle suspension in a turbulent flow can seriously affect the performance of manufactured products in many industrial processes in which the motion of particles cannot be modeled using the numerical method because of the enormous number of particles. Therefore, in this study, a full-scale computational fluid dynamics (CFD) simulation and a 1/5 scaled-down water model experiment were employed to investigate the flow pattern and dynamic behavior of particles in a continuously stirred vessel system. Based on the understanding of the suspension mechanism of settling particles, a particle-suppression device was designed to realize the harmless movement and deposition of particles. The results showed that the flow guidance and division mechanisms of the particle-suppression device led to the inhibition of particle suspensions. In addition, the optimal parameter combination for the device from the water model experiment combined with the orthogonal experimental design, resulted in a 98.3% reduction in the concentration of suspended particles. The suspension of particles was effectively suppressed, which improves product quality and production efficiency. Reliable results can be achieved by combining CFD simulations and water model experiments.

Understanding development of jugular bulb stenosis in vein of galen malformations: identifying metrics of complex flow dynamics in the cerebral venous vasculature of infants.

Introduction: Computational fluid dynamics (CFD) assess biological systems based on specific boundary conditions. We propose modeling more advanced hemodynamic metrics, such as core line length (CL) and critical points which characterize complexity of flow in the context of cerebral vasculature, and specifically cerebral veins during the physiologically evolving early neonatal state of vein of Galen malformations (VOGM). CFD has not been applied to the study of arteriovenous shunting in Vein of Galen Malformations but could help illustrate the pathophysiology of this malformation. Methods: Three neonatal patients with VOGM at Boston Children's Hospital met inclusion criteria for this study. Structural MRI data was segmented to generate a mesh of the VOGM and venous outflow. Boundary condition flow velocity was derived from PC-MR sequences with arterial and venous dual velocity encoding. The mesh and boundary conditions were applied to model the cerebral venous flow. We computed flow variables including mean wall shear stress (WSSmean), mean OSI, CL, and the mean number of critical points (nCrPointsmean) for each patient specific model. A critical point is defined as the location where the shear stress vector field is zero (stationary point) and can be used to describe complexity of flow. Results: The division of flow into the left and right venous outflow was comparable between PC-MR and CFD modeling. A high complexity recirculating flow pattern observed on PC-MR was also identified on CFD modeling. Regions of similar WSSmean and OSImean (<1.3 fold) in the left and right venous outflow channels of a single patient have several-fold magnitude difference in higher order hemodynamic metrics (> 3.3 fold CL, > 1.7 fold nCrPointsmean). Specifically, the side which developed JBS in each model had greater nCrPointsmean compared to the jugular bulb with no stenosis (VOGM1: 4.49 vs. 2.53, VOGM2: 1.94 vs. 0, VOGM3: 1 vs. 0). Biologically, these regions had subsequently divergent development, with increased complexity of flow associating with venous stenosis. Discussion: Advanced metrics of flow complexity identified in computational models may reflect observed flow phenomena not fully characterized by primary or secondary hemodynamic parameters. These advanced metrics may indicate physiological states that impact development of jugular bulb stenosis in VOGM.

Dietary diversity, sociality, and the evolution of ant gustation

Ants have remarkably diverse diets and extraordinary species richness, making them an excellent model system to study the evolution of taste. In this entirely eusocial clade, food choice and the mechanisms that regulate feeding have both individual and social dimensions. How taste receptors and sensory processing drive food preferences to generate dietary breadth in ants is poorly understood. It is additionally unclear how elements of colony organization such as division of labor and social food flow impact the mechanistic basis and evolution of taste. Previous work on dipteran, lepidopteran, and hymenopteran gustatory systems, while foundational, provide limited insights into ant dietary specialization. Here we synthesize and analyze research on ant gustation to identify mechanisms, sociobiological correlates, and phylogenetic patterns. We discuss the current state of genomic analyses of taste and future research. We propose that strikingly polymorphic species of Pheidole, Cephalotes, Camponotus, and leafcutter ants (Atta and Acromyrmex) offer compelling social systems to explore adaptive variation in gustation because of their pronounced division of labor in which morphologically, behaviorally, and neurally differentiated workers vary in feeding behavior. Research on ant gustation within and among species will advance our understanding of sensory systems and provide insight into the impact of taste on the evolution of species diversity and how social organization influences gustation.

SU JET POMPALARININ PERFORMANSI VE KATI-SIVI KARIŞIM TAŞIMACILIĞINDA UYGULANMASI

This present work is focused firstly on an experimental investigation for the optimum design of water jet pumps to be used in the hydrotransport of solid particles through pipeline systems. Experiments were conducted in a closed test loop using five types of jet pumps with various dimensions of the driving nozzle, suction nozzle, mixing chamber, and diffuser employing water as driving and suction fluid. The efficiency of each water jet pump element was analyzed and interpretations of results related to each water jet pump were made about the parts to be considered in the optimum design of a water jet pump. From the experimental results, the water jet pump having the optimum mixing chamber, suction nozzle, driving nozzle location, and cross-sectional dimensions produced a maximum efficiency of about 33%. In the second part of the study, the solid particle carrying capacity of water jet pumps in a pipeline system was studied under saltation, moving bed, and heterogeneous flow regimes by introducing seven different types of solid particles having various concentrations into the closed test loop. The effect of jet pumps on separating solid particles from flow in a region was investigated. A curved form of a by-pass system called the ‘flow division unit’ was added to the main pipeline system and through the flow division unit, then most of the solid particles in the flow were forced to flow towards the suction pipe of the jet pump. As a result of this, only water with very small particle concentrations passed through the centrifugal pumps, and in this way, the wear risk of the centrifugal pump was reduced considerably.

Refined Calculation of Multi-Objective Ecological Flow in Rivers, North China

The concepts and calculation of basic, suitable, and fine ecological flow are put forward, and an integrated multi-method to calculate the ecological flow in rivers under multi-objectives is explored. Based on this, a refined calculation theory and method of a multi-objective ecological flow division based on time and space is proposed. That is, three commonly used methods, namely, the hydrology method, the hydraulics method, and the habitat method, are selected to finely calculate the ecological flow demand at different periods, in different sections, and under different ecological objectives. This approach breaks through the traditional ecological water demand calculation method based on hydrology and develops a river ecological flow calculation method based on water environmental protection objectives. A refined calculation method of ecological flow division based on time and space is developed to ensure that the ecological-hydrological process in rivers and lakes meets the ecological flow demand in different periods, different reaches, and different ecological objectives. Taking eight rivers entering Baiyangdian Lake as an example, the ecological flow demand in different river sections under different ecological objectives at different times is calculated to ensure the ecological flow process. The results show that the range of basic ecological flow demand range is 0.07–3.87 m3/s, the range of suitable ecological flow demand is 0.51~10.74 m3/s, and the range of fine ecological flow demand is 0.71~20.29 m3/s. In terms of spatial distribution, Ping River has the lowest demand for ecological flow, and the Zhulong River has the largest. In terms of the interannual ecological demand, those of the Baigou River, Fu River, Xiaoyi River, and Zhulong River are larger. In the demand process across the year, the demand is the largest from July to September, while the demand is the smallest from March to May. Similarly, most rivers face such problems as a sharp decline in runoff, drying up of the river, and an urgent need to restore ecology in northern China. This study also has insights and reference significance for other regions.

Thermo-economic evaluation of a tri-generation system driven by geothermal brine to cover flexible heating and cooling demand

The main challenge for designing a tri-generation system is to fully cover the heating and cooling demand in district heating networks. In this work, a new flexible tri-generation system driven by geothermal brine is proposed and analysed from a thermo-economic point of view. The proposed system covers the demand of a specific district network according to the climate conditions in Germany. The tri-generation system includes the domestic heat exchanger, the Kalina cycle, and the absorption refrigeration cycle to produce heating, electricity, and cooling. The working fluid of the system is an NH3H2O mixture. The off-design calculation is applied to the design of the heat exchangers as well as to perform annual calculation. The sensitive analysis is studied to evaluate the influence of operational parameters on the system performances. The results show that the ambient temperature and geothermal mass flow division ratio play an indispensable role in the system performance. The mean annual exergy efficiency and levelized cost of electricity are calculated as 46.23% and 0.2245 $/kWh, respectively. An interest rate of less than 5% and the heating mean price greater than 0.15 $/kWh result in an LCOE of less than 0.15 $/kWh.

Development of a calcium sulfoaluminate-Portland cement binary system for twin-pipe 3D concrete printing

Recently, the twin-pipe pumping (TPP) system has been developed for 3D concrete printing which involves pumping two mixtures, typically a Portland cement-based mixture and a pure limestone powder-based mixture that contains an accelerator. Following this, the two mixtures are allowed to be intermixed in a static mixer placed just prior to the nozzle which causes immediate stiffening and a very high buildability for the printed concrete post-extrusion. However, the flow division pattern produced by the mixing baffles of the static mixer results in striations consisting of unmixed limestone powder resulting in weak zones that lower the mechanical strength of the printed element. In this study, we present a TPP system consisting of Portland cement-based mixtures and a borated calcium sulfoaluminate (CSA) cement-based mixture. The mixtures are capable of reacting independently with water as compared to the pure limestone powder-based mixture. After getting blended in the static mixer right before extrusion, the retardation in the borated CSA cement is destroyed by the alkaline component contained in the other stream, leading to the rapid hardening and a high construction rate post extrusion from the nozzle. The hydration characteristics were studied using a Vicat penetrometer, isothermal calorimetry, and ultrasonic pulse velocimetry, while the early age mechanical behavior was characterized by using uniaxial unconfined compression and slow penetration tests. Results indicate that Portland cement alone cannot produce enough alkalinity to destroy the ulexite phase and reinitiate the hydration of CSA cement, while adding a nominal dosage of calcium hydroxide can provide enough increase in pH to design a system suitable for the stiffening control. However, abundant calcium hydroxide would reduce the hydration rate at later ages due to the dilution effect, as indicated by the P-wave velocity evolution and yield stress evolution. In addition, the hardened behavior of printed elements was studied by performing compression and flexural tests. Results show that the CSA-Portland cement binary binder system avoids the formation of weak zones and hence improves the mechanical behavior.

Flow division under a steady flow mode

Many scientists have been involved in the division of open streams. Existing methods for calculating fission nodes do not allow choosing their optimal designs that create a favorable regime for dividing flows. Most of the available results of studies of fission nodes are scattered, non-systematic, and in some cases, contain data that do not coincide with each other. The conducted studies of division nodes were carried out mainly for the steady flow regime; the flow turbulence issues in the flow division section have been little studied. However, in practice, an unsteady flow regime and an increase in flow turbulence are often observed, which leads to complex channel processes in the water intake area. The aim of the work is to develop a refined method for the hydraulic calculation of flow division nodes with a calm flow regime. This goal is achieved by an analytical solution to the problem of determining the water depth in the nodes of flow division under a steady flow regime. The paper uses theoretical studies using the equation for changing the momentum, laboratory studies on a hydraulic model, field surveys of existing water intake units, and an analysis of the experimental data available in the literature on this issue. According to the theoretical studies, calculated dependencies were obtained to determine the depth of the main flow in front of the fission node. The equation is a cubic equation concerning the OX axis and a quadratic equation concerning the OY axis. These two equations are solved independently of each other and are intended to determine the flow depth h1, which is established before the fission node. Taking into account the simplicity of the solution for practical calculations, we recommend the first dependence, and the second dependence is proposed for performing control calculations.