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Structural design parameters always impact the buckling properties of the composite shells due to the differences in the anisotropy of the materials and the varying enhancement capabilities of each component. This paper aims to analyze the parametric effect on the buckling load and optimize the design parameters of metal-composite shells with voids under hydraulic pressure. Firstly, the theoretical model of buckling load is established based on the microscopic model of hybrid materials and the Galerkin method. Then, four design parameters including fiber volume content, winding angles, and CNTs volume content are selected to discuss the parametric effect on the critical buckling load. Further, the global sensitivity analysis is conducted to determine the influence rank, and the GA-PSO algorithm is used to confirm the optimal parametric combination. The results imply that the fiber volume content and internal and external helical symmetrical angles significantly affect the buckling load. Besides, The winding layers of internal and external helical symmetrical angles enhance the hydraulic resistance of the anti-symmetric structure. The middle helical layer can be influenced by the outer layer, leading to directional changes in the critical buckling load at an angle of around 50°. [ABSTRACT FROM AUTHOR]

The investigation into the influence of microenvironmental evolution, induced by calcium leaching on chloride transport in concrete in pressurized water environments, encompassed analysis of aspects such as the solid phase composition, microstructure characteristics, pH value distribution, free and total chloride concentrations using X‐ray diffraction (XRD), Thermogravimetric (TG), Mercury intrusion porosimetry (MIP), Scanning electron microscopy/Energy dispersive spectrometer (SEM/EDS), and titration tests. The results exhibit a weakening of the diffraction peaks of Ca(OH)2 (CH) in the XRD spectra over time under hydraulic pressure. Throughout the calcium leaching procedure, there was an increase in the proportion of pores with diameters exceeding 100 nm. The pH distribution notably followed a pattern where it initially increased, then decreased, ultimately stabilizing at a distinct level. As exposure progressed from the surface to the interior of the concrete, hydroxide ions accumulated predominantly at 10–20 mm. According to the calcium leaching characteristics under pressurized water conditions, concrete can be sectioned into four zones. Specifically, there is a decrease in calcium ions and pH value in concrete Zone 1 near the exposure surface, indicative of a corresponding decrease in the chloride binding capacity. Concrete Zone 2 shows enrichment of hydroxide ions enhances Friedel's salt stability, while leached calcium amplifies the chloride adsorption of ≡SiOH. These effects collectively trigger an increase in both pH and chloride binding capacity. [ABSTRACT FROM AUTHOR]

In this work, reverse osmosis and forward osmosis membranes were prepared using base cellulosic polymers with ZrO2. The prepared membranes were rolled on the spiral-wound configuration module. The modules were tested on a pilot unit to investigate the efficiency of the RO membrane and the hydraulic pressure effect on both sides of the FO membranes. The RO membrane provided a rejection of 99% for the seawater desalination, and the brine was used as a draw solution for the FO system. First, seawater was used as a draw solution to indicate the best hydraulic pressure, where the best one was 3 bar for the draw solution side, and 2 bar for the feed side, where the water flux reached 48.89 L/m2·h (LMH) with a dilution percentage of 80% and a low salt reverse flux of 0.128 g/m2·h (gMH) after 5 h of operation time. The integrated system of RO and forward-assisted osmosis (PAO) was investigated using river water as a feed and RO brine as a draw solute, where the results of PAO indicate a high-water flux of 68.6 LMH with a dilution of 93.2% and a salt reverse flux of 0.18 gMH. Therefore, using PAO improves the performance of the system. [ABSTRACT FROM AUTHOR]

The resistance of thermoset polymer pipes to compressive forces is a concern in the reliability of piping infrastructure. To maintain the reliability of these piping systems, it is imperative to understand and improve the resistance of pipes. The use of polyethylene (PE) rope as Reinforce Polymer Pipe (RPP) composite material was tested with Short-Time Hydraulic Pressure to determine the stress-strain distribution as well as the durability of its mechanical properties. This study used 4mm diameter polyethylene rope arranged radially coiled inside a 40cm diameter polymer pipe with a thickness of 1cm using a mixture of Unsaturated Polyester Resin (UPR), fly ash, sand, catalys and cobalt. The test results show that the composite material has strong mechanical properties and is resistant to hydraulic compressive forces with an average deformation of 8.2 mm with an average maximum load of 33.57kN with the polymer experiencing cracks and damage but the polyethylene rope remains in good condition and has good ductile or elastic properties against compression without significant damage. The highest positive mean strain value of 0.4. The graph displays strain values that are continuously positive up to 50-100 seconds and then drop to negative values quickly indicating that the polymer pipe provides good resistance at the beginning of 50-100 seconds and then experiences damage but the pipe can still return to its original shape with damage to the polymer having an average maximum stress value of 5.23 Mpa with an average duration of 266 seconds while the lowest stress value is 3.34 Mpa.

The interaction between the surrounding rock and the support structure in a circular water conveyance tunnel with lining comprises two main aspects: internal and external hydraulic pressures, and the contact load between the post-excavation lining and the surrounding rock. There is currently no reasonable calculation method to consider both factors simultaneously. Therefore, by utilizing the assumption of smooth contact between the surrounding rock and the lining, an analytical model for a circular water conveyance tunnel with lining is developed through the complex function method. Smooth contact indicates continuity of radial contact stress, coordination of radial displacement, and the absence of shear stress transmission. Considering the inner and outer boundary stress conditions of the lining, two sets of undetermined analytical functions are established, corresponding to internal and external water pressure, as well as the contact stress between the surrounding rock and the lining. Ultimately, the stress and displacement components at any point within the surrounding rock and lining can be derived under the conditions outlined in this study. The analytical model elucidates the mechanism of load transfer within the circular water conveyance tunnel with lining, considering the combined effects of internal and external water pressure and excavation loads. Of particular note, it quantifies the restrictive impact of external water pressure on lining hydrofracturing when subjected to high internal water pressure. Additionally, the model offers a theoretical foundation for designing and assessing support structures for use in long-distance water conveyance projects. [ABSTRACT FROM AUTHOR]

Frost damage on the concrete surface might be aggravated when freezing occurs in the presence of a salt solution, like sea water or de-icing salt. A possible mechanism behind this combination of frost and salt is discussed. When freezing takes place in pure water, ice formed at the surface will block inflow of water to the concrete, but it will cause drying of the concrete. When freezing occurs in salt solution, unfrozen water (brine) can enter the concrete surface and make the concrete completely saturated. When pore water freezes, it exerts pressure. The effect of air-entrainment is favourable since it reduces the stresses. A calculation is made of the air requirement for concrete with w/c-ratio 0.45.

The KR resistance curve for hydraulic crack propagation in a concrete beam was determined and discussed. A semi-analytical method was introduced to calculate the hydraulic crack propagation in concrete. A series of concrete beams with various hydraulic pressures and initial crack depths were tested, and the hydraulic crack propagation in these beams was calculated. The calculated P-CMOD curves were first verified, and then the calculated KR resistance curve for hydraulic crack propagation was determined. Based on the test results and calculation results, the following conclusions can be drawn: The proposed analysis method can accurately predict the hydraulic crack propagation process in concrete. The KR resistance to hydraulic crack propagation in concrete decreases with the increase in hydraulic pressure but is less influenced by the initial crack depth of the test beams. In addition, the concrete beams collapse immediately under hydraulic fracturing once the KIw curve reaches the KR resistance curve. This indicates that the failure of concrete structures under hydraulic fracturing occurs immediately once the driving force of crack propagation, dominated by the hydraulic pressure in the crack, becomes significant. [ABSTRACT FROM AUTHOR]

In this work, reverse osmosis and forward osmosis membranes were prepared using base cellulosic polymers with ZrO2. The prepared membranes were rolled on the spiral-wound configuration module. The modules were tested on a pilot unit to investigate the efficiency of the RO membrane and the hydraulic pressure effect on both sides of the FO membranes. The RO membrane provided a rejection of 99% for the seawater desalination, and the brine was used as a draw solution for the FO system. First, seawater was used as a draw solution to indicate the best hydraulic pressure, where the best one was 3 bar for the draw solution side, and 2 bar for the feed side, where the water flux reached 48.89 L/m2·h (LMH) with a dilution percentage of 80% and a low salt reverse flux of 0.128 g/m2·h (gMH) after 5 h of operation time. The integrated system of RO and forward-assisted osmosis (PAO) was investigated using river water as a feed and RO brine as a draw solute, where the results of PAO indicate a high-water flux of 68.6 LMH with a dilution of 93.2% and a salt reverse flux of 0.18 gMH. Therefore, using PAO improves the performance of the system.

This study experimentally investigated the variations in pore structure, mechanical property and permeability of concrete under sulfate attack exposed to freeze–thaw cycles, and examined the relationship between pore structure, stress, and permeability. The results indicate that before 10 cycles, the original pores in the specimen are filled with the reaction products of sulfate and concrete matrix. Compared with the specimen at 0 cycles, it is denser with a reduction in T2 area, an increase in peak stress, and a decrease in initial permeability. With the increase in the number of cycles, the accumulation and expansion of ettringite and gypsum in the product lead to the subsequent enlargement of pores, more liquid enters the interior of the specimen, and the frost heave effect caused by the freeze–thaw dominates. Therefore, the mesopores and macropores in the specimen are developed, the fractal dimension is reduced, and the T2 area is increased. Macroscopically, the peak stress decreases and the initial permeability increases. Besides, the existence of hydraulic pressure weakens the mechanical properties (peak stress and deformation modulus) of the specimen, increases the lateral deformation and improves the permeability. [ABSTRACT FROM AUTHOR]

Low-permeability deposits currently yield insufficient metal recovery using in-situ recovery (ISR) due to the weak interaction between lixiviant solution and the ore body as a result of low fluid flow and mineral/lixiviant contact. To improve the lixiviant/ore interaction, the use of a solution pulsing method (intermittent rather than continuous pumping) to improve the mass transfer of ions and fluid flow in such deposits could be an option. Solution pulsing alters the solution flow and mass transfer at the microscale between low- and high-permeability regions and can result in a higher overall mass transfer. This paper reports on research in which laboratory-scale solution pulsing-ISR experiments were undertaken to assess the effects of various parameters on lixiviant movement through ideal synthetic core samples. The concentration of lixiviant solution was tracked. The findings revealed that when the pump resting period was too long, the pulsed pumping was inefficient. A short pumping on-and-off time (30 min) was found to be more efficient. The results also confirmed that an increase in the hydrostatic pressure that drives the pumping increased the migration of ions. For the most effective pumping parameters, the effect of synthetic core sample permeability was also measured to confirm that a lower permeability results in a lower ion movement, as is expected from continuous pumping experiments. [ABSTRACT FROM AUTHOR]

The new-type stainless steel–concrete–carbon steel double-skin tubular (SCCDST) members, characterized by their exceptional corrosion resistance and mechanical bearing capacity, have promising applications in ocean engineering, particularly in deep-water engineering. The external hydraulic pressure and interfacial action of various materials intensify the complexity of composite performance of SCCDST members. This paper describes an analytical investigation on the concentric compressive performance of SCCDST members under external hydraulic pressure. The full-range mechanism, including load–displacement response, bearing capacity contribution, and contact pressures, was investigated through the finite element (FE) model that was validated by the failure mode, bearing capacity, and response of axial load versus strain. Subsequently, influences of key geometric–physical parameters were analyzed, e.g., diameter-to-thickness ratios (Do/to, Di/ti), material strengths (fyo, fyi, and fc), hollow ratios (χ), and water depths (H). Typical results indicate that: the initial active confinement action derived from the hydraulic pressure can enhance the interfacial contact pressure and axial compression capacity of SCCDST members due to the tri-axial compression state; the enhancement of confinement effect is mainly from the interfacial interaction between outer stainless steel tube and concrete infill; influence of water depth on bearing capacity cannot be ignored, e.g., the bearing capacity of an SCCDST member with larger hollow ratio (χ = 0.849) is not enhanced under a higher hydraulic pressure (H = 900 m) because of the cross-sectional buckling failure risk. Finally, a modified method considering the effect of water depth was proposed and verified for SCCDST members under hydraulic pressure. [ABSTRACT FROM AUTHOR]

The water leakage through segmental joint gaskets has become a major concern that adversely affects the normal serviceability of underwater shield tunnels throughout the construction and operational periods. Therefore, it is of great significance to investigate the sealing performances of the joint gaskets, which directly helps evaluate the waterproof capacity of underwater shield tunnels. To date, the numerical modeling plays an irreplaceable role in the analysis on the waterproof capacity of the joint gaskets. Nevertheless, conventional methods tend to ignore the self-sealing effect induced by the water seepage pressurization, thus failing to reveal the progressive evolution of the water infiltration process through the joint gasket. To remedy this defect, this paper proposed a novel numerical model to simulate the penetration process of the sealing gasket based on the Python language-enabled secondary programming in the ABAQUS software, which could fully consider the superimposed seepage squeezing effect. Based on the proposed model, the waterproof failure process and the dynamic contact stress of the gasket’s water seepage path subject to excessive hydraulic pressure were thoroughly investigated. Moreover, indoor tests on the waterproof capacity of the gasket were also performed to validate the proposed model. It is found that the numerical results from the developed model are consistent with the experimental results. This research will contribute to better understanding of the gaskets’ hydraulic penetration process and more accurate prediction of the maximum waterproof capacity in underwater shield tunnels.

This review of bone perfusion introduces a new field of joint physiology, important in understanding osteoarthritis. Intraosseous pressure (IOP) reflects conditions at the needle tip rather than being a constant for the whole bone. Measurements of IOP in vitro and in vivo, with and without proximal vascular occlusion confirm that cancellous bone is perfused at normal physiological pressures. Alternate proximal vascular occlusion may be used to give a perfusion range or bandwidth at the needle tip more useful than a single IOP measure. Bone fat is essentially liquid at body temperature. Subchondral tissues are relatively delicate but are micro-flexible. They tolerate huge pressures with loading. Collectively, the subchondral tissues transmit load mainly by hydraulic pressure to the trabeculae and cortical shaft. Normal MRI scans demonstrate subchondral vascular marks which are lost in early osteoarthritis. Histological studies confirm the presence of those marks and possible subcortical choke valves which support hydraulic pressure load transmission. Osteoarthritis appears to be at least partly a vasculo-mechanical disease. Understanding subchondral vascular physiology will be key to better MRI classification and prevention, control, prognosis and treatment of osteoarthritis and other bone diseases.

The interaction between the surrounding rock and the support structure in a circular water conveyance tunnel with lining comprises two main aspects: internal and external hydraulic pressures, and the contact load between the post-excavation lining and the surrounding rock. There is currently no reasonable calculation method to consider both factors simultaneously. Therefore, by utilizing the assumption of smooth contact between the surrounding rock and the lining, an analytical model for a circular water conveyance tunnel with lining is developed through the complex function method. Smooth contact indicates continuity of radial contact stress, coordination of radial displacement, and the absence of shear stress transmission. Considering the inner and outer boundary stress conditions of the lining, two sets of undetermined analytical functions are established, corresponding to internal and external water pressure, as well as the contact stress between the surrounding rock and the lining. Ultimately, the stress and displacement components at any point within the surrounding rock and lining can be derived under the conditions outlined in this study. The analytical model elucidates the mechanism of load transfer within the circular water conveyance tunnel with lining, considering the combined effects of internal and external water pressure and excavation loads. Of particular note, it quantifies the restrictive impact of external water pressure on lining hydrofracturing when subjected to high internal water pressure. Additionally, the model offers a theoretical foundation for designing and assessing support structures for use in long-distance water conveyance projects.

The hydraulic pressure head of the flowing water (between the entrance and exit pipes) in water distribution networks depends on the length and the slope of these pipes, which can represent the head losses for each meter length, where the slope and length of the water supply network pipes are dependent on specified datum ground elevations. This ground elevation may result in a reduction in head losses with hydraulic grade pressure. As a result, the precision of the measured data used to observe ground elevations is critical to decrease the error of these losses and apply an accurate local reference. It's critical to comprehend the implications of using Geographic Information System (GIS) application technology for water distribution network models to evaluate the hydraulic grade head with Iraqi Geodetic Reference. These GIS input data are based on an analysis of the relationship between selected spatial data resolution and the precision of the expected hydraulic head for selected stations with a distribution network. This research aims to review the literature and try to track the conversion of geodetic references and datums to accurately identify the hydraulic pressure for the selected locations of the water supply network. It was found that recent researches tend to use GIS application to create novel methods to reduce head losses and error. [ABSTRACT FROM AUTHOR]

The rock bridges sandwiched in incipiently jointed rock mass were considered as barriers that block the fluid seepage, and provide certain shear strength reservation. For better revealing the influence of hydraulic pressure on the failure behaviour of rock bridges, direct shear tests were carried out through a newly proposed method on rock samples that contain two parallel incipient joints. By developing the gypsum-silicone pad coupling samples, a conventional triaxial test system was qualified to implement direct shear tests with satisfied sealing capability. The results showed that the rock bridges could be failed through the tensile failure, shear failure and mixed failure mechanism. The hydraulic pressure would facilitate the tensile failure mechanism and induce rougher fracture surfaces; while the normal stress would facilitate the shear failure mechanism and induce less rough fracture. The hydraulic pressure reduced the global shear strength of the rock block through reducing the efficient normal stress applied on the rock bridge area, which was highly dependent on the joint persistence, k. Moreover, because of the iterating occurrence of the hydraulic pressure lag with the fracture propagation, the rock bridge failure stage in the shear stress-shear displacement curves displayed a fluctuation trend.

The hydraulic pressure head of the flowing water (between the entrance and exit pipes) in water distribution networks depends on the length and the slope of these pipes, which can represent the head losses for each meter length, where the slope and length of the water supply network pipes are dependent on specified datum ground elevations. This ground elevation may result in a reduction in head losses with hydraulic grade pressure. As a result, the precision of the measured data used to observe ground elevations is critical to decrease the error of these losses and apply an accurate local reference. It's critical to comprehend the implications of using Geographic Information System (GIS) application technology for water distribution network models to evaluate the hydraulic grade head with Iraqi Geodetic Reference. These GIS input data are based on an analysis of the relationship between selected spatial data resolution and the precision of the expected hydraulic head for selected stations with a distribution network. This research aims to review the literature and try to track the conversion of geodetic references and datums to accurately identify the hydraulic pressure for the selected locations of the water supply network. It was found that recent researches tend to use GIS application to create novel methods to reduce head losses and error.

Pre-existing joints within a rock mass has a significant effect on the hydro-mechanical properties of the rock mass. The study investigates the hydro-mechanical properties of rock-like materials with intermittent joints under different confining and hydraulic pressures. Cylindrical specimens containing two sets of parallel pre-existing joints were prepared, and the hydro-mechanical experiments under different hydraulic pressures were carried out using a servo-controlled rock triaxial testing system. The test results show that the strength, permeability and deformation properties of the specimens were influenced by the hydraulic pressure. The four stages of evolution of permeability in the deformation process is closely correlated with the development of joints and cracks within the specimen. The relations between volumetric strain and permeability were analyzed and discussed. It is found that the exponential function describes the permeability and volumetric strain relation well in the contraction stage. When the fluid pressure is high, the fluid pressure has a larger impact on the specimen failure mode than the pre-existing thin joints within the specimen in this test. [ABSTRACT FROM AUTHOR]

The potential of sudden water accidents induced by damage to the bottom slab that forms a water channel due to the action of karst water calls for research on the damage law of coal seam floors under the coupling effect of mining and karst water. In this study, the coupling situation of karst water and floor rock was analyzed based on the theory of rock mechanics and fracture mechanics, combined with the actual geological conditions of a coal seam floor. The law of water-rock coupling was investigated using theoretical analysis and mechanical tests. Results indicate that the strength of the bottom slab rock decreased significantly when the karst pore water was coupled with the bottom slab rock. A three-dimensional numerical model was established using FLAC3D software to simulate the mining situation of the working face under different water pressures. By analyzing the stress change, water pressure change, and plastic zone damage of the bottom slab, it was discovered that the damage effect of karst water pressure on the bottom slab continues to increase when the water pressure is greater than 3 MPa. The impact caused by water pressure greater than 6 MPa occurs gradually. Analysis of measures to prevent and control sudden water on the bottom slab indicates that grouting reinforcement can effectively prevent and control the bottom slab karst sudden water problem. [ABSTRACT FROM AUTHOR]

The triaxial compression tests under different hydraulic pressures and low confining pressure were carried out to study the hydraulic pressure effect on the mechanical properties and permeabilities of layered rock mass. In general, the results show that the increase of hydraulic pressure reduces the peak strength of layered rock mass and the layer structure changes the mechanical properties of rock mass. With the increase of hydraulic pressure, the peak strength of layered rock mass decreases sharply and then slows down. The peak permeabilities of layered rock mass occurred later than the time when the strength come to the peak. The increase of hydraulic pressure will accelerate the propagation of cracks and significantly enhance the peak permeability of layered rock mass. With the increase of the layer number, the effect of hydraulic pressure becomes more distinct. The initial permeability and the peak permeability increase largely. The increase of hydraulic pressure promotes the expansion and penetration of cracks, so the rock mass develops from tensile failure to the composite failure forms including shear failure and interfacial shear slip failure. [ABSTRACT FROM AUTHOR]

Mining systems for ore deposit extraction with the backfilling of the goaf solve the problem of preserving the surface and the complete extraction of rich ores. This paper considers the filling of mined-out stopes with a viscous fluidal solution for the formation of an artificial strong massif, which results in a conglomerate formed on contact with the ore deposit. It was established that exogenous fracturing at the Pivdenno-Belozirske deposit significantly affects the stability of the sides and ceilings in the chamber. This phenomenon can be observed at the first stage of processing. At chambers (the second stage of processing), the artificial rock mass is exposed. It has been established that the chamber mining systems do not ensure the operational stability of the vertical outcrop in the zones of exogenous intensive fracture of the rock mass, especially in the places where they intersect. The zonal location of intense fracture was established along the strike and dip of the steep ore deposit, as was its importance in the formation of rock fallouts. An analytical solution algorithm has been developed to determine the penetration of the backfilling mixture in the plane of the intersection of zones of intense cracking, with opposite azimuths of incidence at steep angles of macrocracking. The features of penetration into microcracks of the backfilling mixture used at the mine, which are affected by their granulometric and physicochemical compositions, have been determined. The influence of the height of the layer and the procedure of backfilling the chamber space in the liquid phase on the formation of the necessary pressure for the opening of a microcrack was studied. The priority of backfilling the exogenous macrocracks with significant gaps and those between tectonic blocks with mixtures has been analytically substantiated and confirmed by experimental methods of research in the mine. [ABSTRACT FROM AUTHOR]

This study investigated the coupled effect of calcium leaching and chloride erosion on concrete subjected to hydraulic pressure by combining experiments and numerical simulations. Several tests including titration, pH, XRD, TG, MIP, and SEM-EDS were employed to analyze chloride concentration, pH value, solid phase compositions, and microstructure of concrete under hydraulic pressure. Concurrently, a model based on the physicochemical interactions between the pore solution and the hydration products was constructed to elucidate the process of calcium leaching and multi-ion transport. The experimental and simulation results reveal that hydraulic pressure accelerates calcium leaching in concrete, leading to a maximum porosity that reaches 1.5 times the initial porosity after a year. In addition, both the pH value and chloride binding capacity in the zone close to the exposure surface decrease. The enrichment of Ca2+ and OH− occurs at a specific depth within concrete during the calcium leaching process, and over time, this enrichment effect grows increasingly significant. Along the depth within the concrete, a transient increase in chloride binding capacity can be observed, which can be attributed to OH− and Ca2+ enrichment. [ABSTRACT FROM AUTHOR]

The new-type stainless steel–concrete–carbon steel double-skin tubular (SCCDST) members, characterized by their exceptional corrosion resistance and mechanical bearing capacity, have promising applications in ocean engineering, particularly in deep-water engineering. The external hydraulic pressure and interfacial action of various materials intensify the complexity of composite performance of SCCDST members. This paper describes an analytical investigation on the concentric compressive performance of SCCDST members under external hydraulic pressure. The full-range mechanism, including load–displacement response, bearing capacity contribution, and contact pressures, was investigated through the finite element (FE) model that was validated by the failure mode, bearing capacity, and response of axial load versus strain. Subsequently, influences of key geometric–physical parameters were analyzed, e.g., diameter-to-thickness ratios (Do/to, Di/ti), material strengths (fyo, fyi, and fc), hollow ratios (χ), and water depths (H). Typical results indicate that: the initial active confinement action derived from the hydraulic pressure can enhance the interfacial contact pressure and axial compression capacity of SCCDST members due to the tri-axial compression state; the enhancement of confinement effect is mainly from the interfacial interaction between outer stainless steel tube and concrete infill; influence of water depth on bearing capacity cannot be ignored, e.g., the bearing capacity of an SCCDST member with larger hollow ratio (χ = 0.849) is not enhanced under a higher hydraulic pressure (H = 900 m) because of the cross-sectional buckling failure risk. Finally, a modified method considering the effect of water depth was proposed and verified for SCCDST members under hydraulic pressure.

The role of coal mine underground reservoirs (CMUR) in ‘guide storage and use’ greatly solves the problem of mine water waste. Replenishment and prediction of reservoir water sources provide an important support for the successful development of key technologies concerning CMUR. To study water replenishment for CMUR, the hydrogeological conditions of the Shendong mining area were investigated as an example. Based on the relationship between the development height of the ‘two belts’ of shallow coal seams and the relative occurrence of location of aquifers, the aquifers are generalized and classified according to occurrences location. Taking Bulianta coal mine as the research background, a discrete element fluid–solid coupling numerical simulation model is constructed to analyze the development characteristics of mining-induced fractures after coal seam mining, and the water replenishment channel of the CMUR is determined. On this basis, analysis is made on the change law of water pressure in the aquifer, aquifuge and coal seam roof under mining action. Taking hydraulic head pressure and water velocity as the judgment basis, prediction and evaluation are made on the water replenishment capacity of CMUR. The research results can provide references for coal mine safety production and mine water protection and utilization. HIGHLIGHTS Based on the water-conducting fractured zone, the occurrence type of ‘coal-water’ is generalized.; The change law of aquifer under different ‘coal-water’ conditions is revealed.; The source and amount of water supply for CMUR were obtained under different conditions.;

The hydraulic erosion of the rock mass within dam spillways must be considered when assessing the stability of dam infrastructures. As this erosion results from the interaction between water and the rock mass, commonly applied methods to evaluate this phenomenon use the notion of a threshold line, a correlation between the water's erosive force and the resistance of the rock mass against erosion. These methods are empirical or semi-empirical, and they have limitations regarding the characterization of this phenomenon. These methods are based on specific hydraulic and rock mass parameters, including a number of parameters that are irrelevant to the erosion process; thus, there is a need to upgrade the existing methods or to seek new solutions to characterize hydraulic erosion. We present a laboratory-scale physical model to determine the effects of rock mass parameters on erosion. This model is designed to determine individual and interactive effects of several hydraulic and rock mass parameters on erosion, including joint opening, block size, joint shear strength, and the nature of potentially erodible surfaces, as well as water pressure (static and dynamic), variations of flow rate and velocity, and channel roughness. Highlights: Design of a reduced physical model of a spillway. Identification of various rock mass parameters controlling rock resistance against the erosive force of water. Identification of the key parameters affecting the hydraulic load within spillways. Multiple geomechanical parameters of the rock mass compared to the erosive force of water. [ABSTRACT FROM AUTHOR]

Active fluid transport across epithelial monolayers is emerging as a major driving force of tissue morphogenesis in a variety of healthy and diseased systems, as well as during embryonic development. Cells use directional transport of ions and osmotic gradients to drive fluid flow across the cell surface, in the process also building up fluid pressure. The basic physics of this process is described by the osmotic engine model, which also underlies actin-independent cell migration. Recently, the trans-epithelial fluid flux and the hydraulic pressure gradient have been explicitly measured for a variety of cellular and tissue model systems across various species. For the kidney, it was shown that tubular epithelial cells behave as active mechanical fluid pumps: the trans-epithelial fluid flux depends on the hydraulic pressure difference across the epithelial layer. When a stall pressure is reached, the fluid flux vanishes. Hydraulic forces generated from active fluid pumping are important in tissue morphogenesis and homeostasis, and could also underlie multiple morphogenic events seen in other developmental contexts. In this review, we highlight findings that examined the role of trans-epithelial fluid flux and hydraulic pressure gradient in driving tissue-scale morphogenesis. We also review organ pathophysiology due to impaired fluid pumping and the loss of hydraulic pressure sensing at the cellular scale. Finally, we draw an analogy between cellular fluidic pumps and a connected network of water pumps in a city. The dynamics of fluid transport in an active and adaptive network is determined globally at the systemic level, and transport in such a network is best when each pump is operating at its optimal efficiency. [ABSTRACT FROM AUTHOR]

This paper aims to provide a new design considering compressive force application in the MR fluid and improve its braking torque by optimizing it. According to the current study, compressing the MR region will increase braking torque compared to no compression. The area covered by an existing model of the conventional disc brake is taken into consideration for the unique design of the MR brake to operate in shear and compression mode, and the required compression given by the hydraulic pressure similar to a conventional disc brake. The suggested MR brake’s structural layout is presented. The Herschel-Bulkley shear thinning model’s mathematical expression for the torque equation for the compression and shear modes is provided. An analytical magnetic circuit is done for the proposed design for determining the relationship between applied current and magnetic field strength as a function of the geometrical and material attributes of the MR brake. Simulation is done on COMSOL software with the help of an AC/DC module, considering the non-linear relationship between the magnetic field and magnetic flux. Simulation results of braking torque achieved with the varying current are determined. The graph displays the braking torque for current in the compression plus shear mode as well as shear mode. After that, optimization is done on the proposed model for optimal design parameters. For optimization, we adopt the most popular Genetic Algorithm (GA) method. Optimization aims to increase the braking torque capacity of the MR brake for the given volume. [ABSTRACT FROM AUTHOR]

With the improvement of agricultural equipment level in China, agricultural machinery is developing towards large, wide and efficient trend. Large and medium-sized no-tillage sowing equipment can not only reduce production cost, but also meet the agronomic requirements of no-tillage operation in northern China, and can increase crop yield. However, its wide width and heavy weight lead to the problems of difficult transportation and operation transfer. This study is aimed at the practical application of the medium-sized no-tillage mulch and ridge planting corn seeder as the research object. The medium-sized seeder is connected with seven groups of seeding units with row spacing of 650 mm. On the basis of theoretical analysis, the use of digital prototype, virtual simulation technology to determine the right drill transport platform, through the wheel mechanism and traction mechanism to lateral suspension operation, longitudinal traction transportation, land wheel deformation parameters, arrangement of hydraulic, traction mechanism and transmission ratio adjustment, etc. The transmission system can transfer power to fertilizer shaft and seed shaft according to the specified transmission ratio. The hydraulic electric control system is composed of pressure relay and electromagnetic directional valve to reduce the number of oil inlet and outlet and simplify the operation steps. The simulation results show that the synchronization accuracy of the hydraulic cylinder of the ground wheel mechanism is less than 3.6%. The hydraulic electronic control system is easy to operate and can accurately reach the sequence action position, and the synchronization performance is good. The finite element analysis module of CATIA software was used to analyze the stress and strain of the frame and the ground wheel mechanism. The strength of the frame under the braking state during transportation met the requirements. The stress analysis of the ground wheel mechanism showed that it had good strength and stiffness, and there was a large space for optimization. The total mass of the high mobility frame platform is reduced from 244.0 kg to 178.8 kg, and the mass reduction ratio of the auxiliary ground-wheel mechanism is 26.72%, and the mass reduction ratio of the dual ground-wheel mechanism is 10.96%, which can meet the strength and stiffness requirements of the ground-wheel mechanism, and the optimization effect is significant, and can meet the requirements of transportation and operation. The hydraulic electronic control system test and road transportation vibration test show that the whole machine meets the requirements of various indicators, meet the requirements of mid-sized no-tillage mulch and furrow seeder operation transfer, hydraulic electronic control system can control the hydraulic cylinder to complete the sequence of action, the operation state conversion time of 5min, saving the operation transfer time. Through analyzing the vertical acceleration of the road transportation test vibration, the natural frequency of the vertical vibration at the center of mass of the frame increases with the increase of the vehicle speed, and the increase amplitude decreases gradually. When the driving speed is 10, 15 and 20 km/h, the natural frequency of vertical vibration acceleration at the center of mass is concentrated within 0-3 Hz, and the natural frequency of vertical vibration increases with the increase of driving speed, and the vibration intensity increases rapidly. When the driving speed is 25 km/h, the maximum vertical displacement of the vehicle's center of mass is the largest, which meets the requirement of radial pendulum momentum, and the transportation is safe and stable. In this study, the high maneuvering platform technology was applied reasonably to the compact medium no-tillage mulch and ridge corn seeder, which solved the difficult problem of operation transfer and provided reference for the design of transfer platform of wide range agricultural machinery equipment. [ABSTRACT FROM AUTHOR]

Root pressure is a positive hydraulic pressure that generated by plant roots. As a common physiological phenomenon in many plants, root pressure can drive the sap flow from roots to canopy leaves, which alleviates plant water deficits caused by strong transpiration during the day. It also plays an important role in xylem embolism refilling. At present, there are many explanations for the generation of root pressure. The generally accepted views include the osmotic theory, the metabolic theory, and the uphill water co-transport hypothesis, but the mechanism of root pressure is still the focus of controversy among the plant scientists. There are direct and indirect methods for measuring root pressure, but the more advanced techniques of measuring root pressure still need to be improved. Under the influence of many factors such as aquaporin, genetic factors and habitats, there are differences in the magnitude of root pressure, and moderate root pressure has important significance for crops growth. Therefore, it is of great biological significance to deepen our understanding of root pressure. Here we discussed root pressure from the following perspectives: the definition and mechanism of root pressure generation; plant groups with root pressure; the methods for measuring root pressure; the main factors about influencing root pressure; the significance and implications of root pressure in various fields of plant science studies. Lastly, based on current research topics and some new results on root pressure, we discussed future perspectives on root pressure of plants. [ABSTRACT FROM AUTHOR]

The influence of hydraulic pressure (max. 20 MPa) on the internal damage of cement-based materials is experimentally studied. In order to observe in situ the internal damage of cement-based materials under hydraulic pressure, a new testing apparatus equipped with an X-ray micro-computed tomography (X-μCT) scanner is developed. The behaviors of water infiltration and strain development are evaluated for mortar specimens with different water-to-cement ratios. Although the internal damage of the mortar specimens under hydraulic pressure was not detected by the X-μCT scanner and fluorescent imaging, the mechanical properties tested after hydraulic pressure loadings were altered, indicative of the occurrence of microcracks (

Objectives: To investigate the effectiveness of hydraulic pressure-assisted sinus augmentation (SA) in a rabbit sinus model in terms of radiographical and histological healing. Materials and methods: Bilateral SA was performed in 12 rabbits. Each sinus was randomly assigned to either a hydraulic pressure-assisted SA (test) or a conventional SA (control) group. Healing periods of 2 and 4 weeks were applied (n = 6 for each week). Healing pattern including newly formed bone (NB) and residual bone substitute material (RM) was analyzed with microcomputed tomographically, histologically, and histomorphometrically. Results: No sinus membrane perforation was detected in either group. In the microcomputed tomographic analysis, the test group exhibited higher apico-coronal spread of RM compared to the control group (p < 0.05). Particularly, the test group exhibited several masses of NB out of the cluster of RM. Histologically, the test group showed an elongated shape of the augmented space, whereas the control group generally presented a dome shape. Histomorphometrically, the total augmented area and the area of NB (1.32 ± 0.56 vs. 0.84 ± 0.40 mm2 at 2 weeks, 2.24 ± 1.09 vs. 2.22 ± 0.85 mm2 at 4 weeks) were not significantly different between the test and the control groups at both healing periods (p > 0.05). Conclusion: Hydraulic pressure-assisted SA led to new bone formation in the distant areas from the bony access hole, but similar histological healing pattern to conventional SA. Clinical relevance: Hydraulic pressure-assisted SA is a promising option for treating pneumatized posterior maxilla. [ABSTRACT FROM AUTHOR]

In this study, collets having the same geometry in SAE 4140 and 50CrMo4 material standards and collets having different geometry in 50CrMo4 material standards were examined by ANSYS. Finite element method and subjected to fatigue test under 25 bar hydraulic pressure with 2.2 kW motor with Volt brand. Results received by Siemens brand remote control and finally the comparison has been made. [ABSTRACT FROM AUTHOR]

The technical field of belt tensioning force studied in this paper, in particular, relates to a hydraulic belt tensioning device, including a base, a hydraulic system and a rail fixed on the base, and a tail wheel trolley sliding on the rail; This device can provide a large tension to the tail wheel of the conveyor belt to meet the tension required by the long conveyor belt. At the same time, it can automatically adjust the tension to the tail wheel of the conveyor belt according to the tension of the conveyor belt to realize the dynamic tension control of the conveyor belt; The device prevents belt deviation and material leakage, reduces labor intensity of workers, avoids equipment accidents, and improves industrial production capacity.

In this study, the design of a metal stent which expands under the influence of a difference in hydraulic pressure is presented. Using the action of existing stents as a reference, the joint of the metal stent model is joined, to lock its own elastic force. The maximum energy storage formula was applied to determine if the joint could withstand the elastic force that is integral to the stent model. Simulations of the stent, under the influence of differences in hydraulic pressure, were performed. During simulation, the fluid pressure, the width of the joint of the stent, the angle of the pipe model, and some other parameters, were changed to determine their impact on the stent joint and to explore the differences. [ABSTRACT FROM AUTHOR]

Aim: To present a novel root canal filling technique: Ultrasonic Vibration & Thermo‐Hydrodynamic Obturation (VibraTHO), and its rationale with a series of cases. Summary: The VibraTHO technique was used to fill the root canals of three clinically challenging cases: A C‐shaped mandibular molar with complex anatomy, a C‐shaped mandibular molar with an infected root canal system and a periapical lesion that required retreatment, and apically bifurcating mesiobuccal canals with a common orifice in a maxillary second molar. The cases were followed up for 15, 7 and 37 months, respectively. After follow‐up, normal periapical status was observed without any noticeable radiographic change in the root canal fillings in each case. Periapical radiographs revealed complete healing of the periapical area in cases with pre‐operative periapical lesions. [ABSTRACT FROM AUTHOR]

In order to perform a pressure chamber experiment with a circular cylindrical pressure vessel, the dimensions of the cylinder need to be determined in the range of the maximum externally applied pressure of the chamber to create the collapse process. In this study, the collapse load values from published chamber test results, finite element analysis and the theory of thick cylinders were thoroughly compared in a aluminum cylinder. In order to investigate the effect of collapse load according to the ovality during manufacturing, nonlinear buckling analysis was performed and the collapse load according to ovality was compared. Based on the results, the dimensions of the steel cylinder were determined for the future chamber collapse test.

The pressurized water-rock coupling has a great influence on the long-term stability of rock engineering. In order to study the effect of axial and hydraulic pressure coupling on the creep behaviors of rock, a multi-channel fluid-solid coupling rock rheology system was used to carry out multi-loading creep experiments on the creep behaviors of sandstone. In view of the creep behaviors of the studied sandstone, a three-dimensional nonlinear Nishihara model considering hydraulic pressure was established, and the accuracy of the new model was verified. The research results showed that, with the increase of the hydraulic pressure, the creep strain of sandstone under both the same initial load and multi-step load decreased, whereas the rock creep strength and the maximum acceleration creep rate increased. Under the same hydraulic pressure and initial load, the creep strain increased with the multi-loading increasing, but the creep failure time became shorter. Through the parameter recognition of the newly proposed nonlinear creep model, the comparative analysis of theoretical and experimental results showed that the new creep model can well describe the creep behaviors of the sandstone under the pressurized water-rock coupling. [ABSTRACT FROM AUTHOR]

Sudden flooding is one of the major risks for the drainage sinking construction of deep-water caisson. The damage of inner walls due to hydraulic pressure induced by sudden flooding threatens the labor and structural safety. This study developed the numerical model and analytical method to assess the hydraulic pressure on the inner walls of both the balanced and sudden-sinking caisson under sudden flooding risk. An experimental program of sudden flooding into a caisson specimen was conducted in a water basin to validate the numerical model and the analytical method for balanced caisson. The numerical and analytical methods were then illustrated by an actual engineering practice to show the hydraulic pressure on the inner walls for the caisson under balanced and sudden-sinking state, respectively. The experimental validation and engineering illustration prove that the numerical model is effective in the assessment of hydraulic pressure of caisson under sudden flooding, especially for the complicated case that includes the turbulence effect and sudden sinking, while the analytical method can calculate the quasi-static value of the hydraulic pressure more efficiently. The presented methods provide the engineers with alternative tools to learn more about the sudden flooding risk of the deep-water caisson. [ABSTRACT FROM AUTHOR]

In this paper, a new method for estimating the axial tension of each bolt after the hydraulic tightening, and an appropriate structure for the hydraulic tightening have been proposed. A hydraulic tensioner is frequently used to tighten the pressure vessels by the bolted joints. The hydraulic tensioner can apply higher value and lower variation of the axial tension than the torque tightening. However, the axial tension remaining in the bolt after the hydraulic tightening is less than the initial tension by the hydraulic load, and the ratio of the residual tension to the initial tension, the effective tensile coefficient, is the most critical factor to tighten the pressure vessel securely. Some estimation methods of the ratio considering the stiffness of tightening parts have been proposed. However, there are no previous studies that verified the theory, the characteristics and the appropriate structure for the hydraulic tightening using various bolts, such as a stud bolt, a through bolt and a two-nuts bolt. In this study, we developed some new equations for estimating the effective tensile coefficient of each bolt by considering the compliance at each part of the bolted joint. Then the analysis method of the hydraulic tightening for each bolt was developed by using a finite element model simulated the joint process with the hydraulic tensioner. In addition, we evaluated the effective tensile coefficient of each bolt by the analysis and considered improvement measures of that. As a result, it was clarified that the analysis method and the equations could estimate accurately the effective tensile coefficient and the coefficient of the two-nuts bolt was the highest of the three bolt types. It was confirmed that the coefficient could be improved by locating the foot close to the bolt and reducing the diameter of the bolt-hole.

Well-known frost destruction mechanisms applicable to concrete not exposed to salt are, (1) hydraulic pressure during freezing, (2) growth of ice-bodies in capillaries during freezing. Theories behind these mechanisms are presented. A third mechanism, ice expansion during heating of frozen concrete, is put forward. The validity of a certain mechanisms is discussed by analyzing its ability to explain experimental observations.

A sugarcane harvester is commonly used for mechanized harvesting in the hilly and mountainous areas. However, the cutter disk of the sugarcane harvester cannot automatically adjust with the fluctuation of ridge height, leading mainly to the sugarcane ratoon damage and wastes during the harvesting process. In this study, a data acquisition device was proposed for the cutting pressure of a hydraulic motor in a cutter disk, and then a simulation device was developed for adjusting the cutting height of the cutter disk with the ridge height. The data collection device for the cutting hydraulic motor was installed on the 4GZQ-260 sugarcane harvester. The hydraulic pressure of a cutter disk motor was collected, when the sugarcane was harvested at the planting site in Mingjiang Town, Ningming County, Guangxi, China. The results showed that the hydraulic pressure for the cutter disk of the harvester greatly varied, when cutting sugarcane into the soil and not into the soil, where the planting density and physical characteristics of sugarcane were fixed. A set of automatic control and adjustment device was designed for the height of the cutter disk, with the aid of hydraulic pressure in the cutting system. The device was mainly composed of a cutter disk lifting system, a cutter disk and a hydraulic motor, a data acquisition system of hydraulic pressure and speed. The hydraulic pressure sensor was used to detect the pressure of the hydraulic motor during cutting the sugarcane. The cutter disk lifting system was used to realize the lifting and lowering of the cutter disk according to the pressure value. The pressure of the hydraulic motor was measured, when the cutter disk was no-load, no soil cutting, and cutting into the soil depth of 3cm, and 5cm. The pressure varied greatly when cutting in different depths. The critical pressures were obtained under three conditions, thereby formulating the lifting rules of the cutter disk. A field test was carried out to verify the automatic regulation and control the cutting depth of the cutter disk into the soil, where the benchmark cutting depth was set to be 3 cm, particularly when the height of the sugarcane ridge changed. The test results showed that when the cutter disk advanced at a speed of 0.25 m/s, the maximum error between the cutter disk entering the soil and the preset depth was 0.7 cm. When the cutter disk advanced at a speed of 0.4 m/s, the maximum error between the cutting depth of cutter disk and the preset depth was 0.8 cm, indicating the automatic adjustment of cutting depth according to the ridge height change of sugarcane. The provisions of sugarcane stubble can be less than 3 cm to meet the design requirements. This finding can provide a technical foundation for the automatic adjustment of cutting height for the cutter disk on the sugarcane harvester in the hilly and mountainous areas of China. [ABSTRACT FROM AUTHOR]

Extended high fluctuations of internal water pressure have often been causally linked to pipeline failures in water distribution systems, especially when this exposure has continued over many years. However, as yet, there is little solid quantitative evidence to support this in real water systems. This paper examines the impact of internal pressure and other critical parameters on the integrity of water pipelines in five districts operated by a California water utility. Eight years of data from the utility's Annual Pressure Survey and 25 years of water pipeline failure data were collectively analyzed using spatiotemporal clustering tools and a Poisson regression model. The analytical procedures and results presented in this paper are designed to support both the water utility's short-term operations and its long-term programmatic drinking water pipeline planning and management practices. [ABSTRACT FROM AUTHOR]