Search Results (3,915)

More than 100 small sinkholes, 12 to 50 cm wide and 10 to 80 cm deep, developed rapidly in sandy-clay soils in two adjacent plots in south-central Mississippi, USA, following the installation and operation of a nearby high-capacity water well. The local area is not known for karst features, evaporite dissolution cavities, underground mining, soil erosion around manmade structures, or desiccation fractures of shallow clays. When studied several years after first appearing, the sinkholes had nearly vertical walls, with some cavities widening with depth. Some had tree stumps visible in the center. Further investigation found remnants of stumps or roots in and radiating outward from multiple sinkholes. Installation of piezometers along a transect revealed a continuous hydraulic gradient under the impacted property toward the production well and evidence of reduced overall water levels. The most plausible causes of rapid sinkhole formation are (1) initial partial preservation of tree stumps in soils saturated by a high water table and capillary action in fine-grained surface sediments, (2) lowering of the water table and aeration of near-surface sediments, and (3) accelerated decomposition of stumps faster than soil could creep or cave into the cavities. We propose designating the resulting features as “decomposition sinkholes.” Full article

This paper presents a real-time browser-based platform for thermohydraulic characterization of a compact laboratory heating system, developed using the PolyVR research-grade virtual reality engine. Experimental measurements are retrieved at 1 Hz from a cloud-based database and processed via browser-native computational framework that continuously performs thermophysical modeling, hydraulic analysis and energy balance evaluation. The system calculates the rate of heat transfer (h), overall heat transfer coefficient (U), dimensionless numbers (Re, Pr, Gr, Nu), pump performance, heater efficiency and cumulative thermal energy. PolyVR provides the immersive environment in which the partial digital twin functionality is integrated alongside the browser-based thermohydraulic calculations. The whole system includes support for animations regarding flow diagrams, valve state indicators, thermal field visualization and manipulation of system elements. The system architecture is designed to work on desktops, head-mounted devices, as well as in CAVE (cave automatic virtual environment) systems with remote connection made possible via using ngrok tunnels. The experiments were separated into three categories (steady-state, dynamic and validation). Steady-state and dynamic datasets show that the browser computation with PolyVR achieves high-fidelity thermohydraulic analysis similar to that done in laboratory settings. The steady-state and transient datasets illustrate that browser-based computation provides highly accurate thermohydraulic simulation close to that of the laboratory reference computations. For all experiments performed on the platform, the deviation of measurements does not exceed ±0.5 K in temperature, ±5% in flow rate and ±1% in pressure. The energy balance is closed with a deviation of ±2–3%. Full article

This study presents a rapid design-and-validation framework incorporating resistance optimization for 3D-printed bridge pier geometries. A full-factorial experimental campaign comprising 16 reduced-scale solid pier sections is first conducted by systematically varying upstream fairing length and downstream fishtail length while maintaining constant maximum transverse width and cross-sectional area. The specimens are fabricated using fused deposition modeling (FDM) 3D printing with polyethylene terephthalate glycol-modified (PETG) material and tested in controlled towing experiments driven by a field-oriented control (FOC) motor, with motor torque signals recorded as a proxy for hydrodynamic resistance. The raw data are processed through steady-state trimming, null-test bias correction, and one-dimensional Kalman filtering, after which a root-mean-square (RMS) resistance metric is computed for each geometry. A key finding from the two-way analysis of variance (ANOVA) analysis reveals that fairing length exerts the dominant influence on resistance, followed by the fairing-fishtail interaction, whereas fishtail length alone plays a secondary role. The experimental ranking identifies S13, combining a short fairing with a long fishtail, as the optimal geometry, achieving a 33.6% reduction in RMS torque relative to the circular baseline. Bootstrap resampling confirms that the low-resistance cluster is a robust geometry family rather than a statistically fragile optimum. Then, independent COMSOL Multiphysics 6.3 (COMSOL) topology optimization and transient flow-field simulations are employed as morphology-level validation tools, with the optimized outline converging toward a streamlined profile qualitatively consistent with the experimental findings. The drag decomposition further indicates that pressure drag constitutes the dominant component, suggesting that shape-induced pressure redistribution is the primary mechanism underlying resistance reduction. The proposed framework thus provides a physically grounded, low-cost intermediate step between computational shape generation and detailed engineering validation for resistance-optimized bridge-pier sections, and it can be readily extended to a broader range of pier cross-sections or other hydraulic structures. Full article

Steel storage tanks are erected on site by multi-cylinder hydraulic lifting, conventionally from one power unit feeding all cylinders through a flow divider. Decentralized alternatives have not been evaluated for this task, and modularity in fluid power is rarely quantified. A ten-cylinder device was analyzed as a centralized (C1) and a modular (C3) variant with a servomotor-driven pump at each cylinder; both were decomposed into five functional modules and compared through a directed design structure matrix (DSM). External dependencies per module fell by 38.6% and mean interface complexity by 30.9%, against only 11.1% for interfaces per module: interfaces were thinned, not removed. Internal cohesion rose from 0.583 to 0.805; the total risk priority number, an ordinal expert-assigned indicator, fell from 2253 to 760. C1 was characterized from documentation and was not tested experimentally; a three-module prototype at a length scale of 0.31 was run through sixteen series: open and closed loop, both directions, four disturbance configurations. In open loop, the error left the ±2% band in every series; in closed loop, it stayed inside the band in lifting and over the last 91–92% of stroke in lowering, cutting the drift rate by one to two orders of magnitude. The structural gain corresponds to removing the hydraulic installation and the flow divider, which dominate both the open-loop drift and the failure-mode ranking; the modular device costs about 58% more. Full article

Water-vapor removal from compressed air is governed by the product pressure dew point (PDP), dynamic bed utilization, hydraulic loss, regeneration demand, and cyclic reliability, yet activated-alumina studies are often interpreted from powder Brunauer–Emmett–Teller (BET) area or equilibrium uptake alone. This critical narrative review evaluates where evidence can and cannot be transferred across material, formed-particle, packed-bed, cycle, and field scales. It distinguishes equilibrium capacity, static test capacity, dynamic breakthrough capacity, and usable cycle capacity; conditionally compares desiccants and regeneration modes; and links PDP-defined breakthrough, mass-transfer-zone (MTZ)/length-of-unused-bed (LUB) measures, non-spherical-particle pressure drop, thermal waves, and regeneration endpoints. The available evidence supports several directional conclusions but not universal design values: alkali modification can increase uptake despite lower surface area; forming and binder chemistry alter accessible pores and strength; wall effects and particle geometry require measured hydrodynamic validation; and reported regeneration savings of approximately 27–40% are architecture-specific relative results rather than matched absolute energy benchmarks. A baseline-normalized diagnostic framework separates reversible regeneration faults and feed contamination from material aging and particle/bed degradation. The review identifies the central evidence gap as the absence of matched datasets reporting formed-body properties, adiabatic breakthrough, segmented pressure drop, regeneration energy, and long-cycle failure for the same material. It concludes with a standards-coverage map, a transparent screening sensitivity analysis, and a prioritized validation agenda. Full article

This study presents a 3D-printed prosthetic sole with a flexible toe segment for a bionic lower-limb prosthesis. The design exploits functional material distribution: a load-bearing frame in carbon-filled nylon (PAHT-CF) is combined with a thermoplastic polyurethane (TPU 95A) zone that acts as a passive elastic hinge. Static finite element analysis in SolidWorks Simulation under a 400 N vertical load yields a tip displacement of about 25 mm and a toe-segment deformation near 10 mm. Compression testing on a hydraulic press up to 1000 N produces a peak displacement of around 7 mm without fracture or residual plastic deformation, confirming the suitability of the PAHT-CF/TPU hybrid for low-cost prosthetic feet. Full article

This study presents a displacement feasibility methodology for a closed-center load-sensing hydraulic system intended for industrial forklift applications. The approach combines analytical hydraulic calculations with simulation-based verification in Automation Studio. A Perkins D3900K diesel engine (Bulgarian industrial group Balkancar) and several Danfoss H1 axial piston pump (Danfoss Power Solutions Nordborg, Denmark) displacements were evaluated under engine power limitations. Pump flow, torque demand, hydraulic power, and a power-limited pressure envelope were derived to support engine–pump matching. The results show that oversized pumps significantly reduce allowable pressure, particularly at higher engine speeds. Pump displacements of 45–60 cm³/rev provide the most balanced compromise between pressure capability and practical flow delivery. Full article

Hydraulic transients induced by rapid changes in operating conditions represent a major challenge in the design and safe operation of offshore Firewater systems. During emergency events, such as fire pump start-up or rapid valve operations, pressure waves may propagate throughout the distribution network, generating water hammer effects capable of compromising the integrity and reliability of critical safety equipment. This study investigates the transient hydraulic response of an offshore Firewater ring-main system installed on a Floating Production Storage and Offloading (FPSO) unit using a detailed numerical model developed in PIPENET Transient. Three representative emergency operating scenarios were analysed, including fire pump start-up, deluge valve closure, and monitor valve closure. For each scenario, the hydraulic response of the original system configuration was compared with a modified pressure-protection arrangement involving relocation of the check valve immediately downstream of the fire-pump discharge flange and reduction of the pressure safety valve (PSV) set pressure from 17.5 barg to 16.5 barg. The simulations enabled the identification of critical pressure locations, evaluation of transient pressure propagation, and assessment of the effectiveness of the proposed mitigation strategy. The results demonstrate that the modified pressure-protection arrangement reduces the governing system-level pressure peaks and attenuates transient pressure oscillations under the investigated operating conditions. The proposed engineering methodology provides practical support for the design verification and optimization of offshore Firewater systems and contributes to improving the operational safety and reliability of safety-critical piping networks. Full article

Cavitation erosion severely limits the service life of marine hydraulic components. Magnetron sputtering was utilized to fabricate TiSiN/AlCrTiVNbN high-entropy nitride nanomultilayer films, whose modulation periods ranged from 4 nm to 23 nm. The effects of modulation period on the microstructure, mechanical properties, and cavitation erosion resistance were systematically investigated. All films exhibited a single-phase face-centered cubic structure with a preferred orientation (200) plane. The film with a 6 nm layer period reached the highest hardness (38.9 GPa) and elastic modulus (214.1 GPa), which is due to the many closely fitting interfaces that effectively stopped line defect movement; in cavitation erosion tests in 3.5% salt water, this film had the lowest mass loss (0.8 mg) and its surface stayed in the best condition. Its superior cavitation erosion resistance originates from the synergistic effects of high-density coherent interfaces that obstructed crack propagation, enhanced mechanical properties that provided excellent resistance to plastic deformation, and the formation of a protective oxide layer during cavitation. As this work shows, optimizing the layer period is an effective strategy; it allows the design of strong protective films for ocean use. Full article

Rock–ice avalanches and repeated freeze–thaw cycles pose coupled challenges to baffle-type mitigation structures in high-altitude cold regions. This study used controlled small-scale pull-out tests to quantify changes in baffle–soil friction over 0–30 freeze–thaw cycles and then calibrated a discrete element method (DEM) model to the terminal 30-cycle condition to evaluate baffle geometry, particle size, interparticle cohesion, and pull-out velocity. Moisture redistribution approached equilibrium after approximately 7–10 cycles, whereas the friction response stabilized only after approximately 16 cycles, indicating that hydraulic stabilization preceded mechanical and interfacial stabilization. The friction coefficient decreased from 0.83 before cycling to 0.48 after 30 cycles, corresponding to an attenuation of 42.17%, and the friction force decreased from 130 to 75 N. The decay showed three stages: limited change over 0–3 cycles, accelerated degradation over 3–16 cycles, and a near-plateau thereafter. The DEM results indicate that lateral prop-root projections can increase pull-out resistance by enlarging the mobilized soil volume and enhancing mechanical interlocking; the response also depends nonlinearly on particle size and cohesion. The proposed baffle is therefore presented as a preliminary structural concept rather than a field-ready design. Because the experiments were not performed under complete geometric, kinematic, or dynamic similitude and the DEM calibration represents only one post-freeze–thaw state, the numerical values should be interpreted as laboratory-scale comparative results. Full article

Mexico’s highly biodiverse agro-industrial sector is a cornerstone of its economy, prominently featuring a robust sugarcane industry that ranks seventh globally in sugar production. This industry utilizes 52% of the country’s industrial water resources, hence producing substantial quantities of complex wastewater. To address this critical environmental challenge, this study evaluates a continuous electrocoagulation process applied to sugarcane mill effluents. The study examines the effectiveness of removing essential water quality indicators, chemical oxygen demand (COD), turbidity, and total solids (TSs), total suspended solids (TSSs), and total dissolved solids (TDSs), by evaluating the influence of the hydraulic retention time (HRT) and current intensity. Investigations were performed in a 20 L continuous-flow Imhoff reactor fitted with aluminum electrodes. Ideal operational parameters were attained with a hydraulic retention time of 120 min and a current intensity of 1.5 amperes. Within these parameters, the system attained notable removal efficiencies: 69% for COD, 78% for turbidity, 60% for total solids, 94% for suspended particles, and 55% for dissolved solids. These findings indicate that the incorporation of continuous electrocoagulation into an Imhoff tank design offers a highly efficient and scalable first treatment to reduce the ecological effects of sugarcane agro-industrial effluents. Full article

Constructed wetlands (CWs) are increasingly used for decentralized wastewater treatment and reuse where conventional infrastructure is difficult to sustain. This review integrates evidence on hydraulic reliability, biogeochemical performance, reuse safety, sustainability trade-offs, and process-based modeling, and derives design implications for Neotropical settings. Organic-matter and suspended-solids removal is generally more robust than nitrogen, phosphorus, and pathogen control. More reliable performance is associated with controlled hydraulic loading, solids-limiting pretreatment, stable flow distribution and water levels, and protection against stormwater-driven short-circuiting and clogging. Reuse should therefore be evaluated against fit-for-purpose microbial, nutrient, salinity, and chemical endpoints rather than removal efficiency alone. We propose seasonal monitoring, tracer or residence-time-distribution assessment where decisions depend on hydraulic efficiency, locally calibrated design envelopes, and a minimum reporting set covering climate/season, flow and loading, HRT/HLR, configuration, pretreatment, media, monitoring duration, influent/effluent concentrations, and hydraulic indicators. This study is a structured narrative review with thematic synthesis; literature identification and corpus reporting were informed by applicable PRISMA 2020 principles. Three Scopus searches yielded 593 records; after removal of 37 duplicates, 556 unique records remained. The final thematic corpus comprises 80 reports, of which 30 are present in the Scopus exports and 50 were identified through complementary routes. Full article

The oil and gas industry has emerged as one of the largest consumers of polymer composites, with dissolvable polymers and composites representing one of the most significant technological advancements in this sector. These materials are essential for the manufacturing of high-performance tools such as hydraulic fracturing plugs, which must withstand extreme downhole conditions—temperatures of up to 250 °C and a pressure differential of up to 150 MPa—before dissolving rapidly in wellbore fluids to facilitate continuous production. Unlike traditional dissolvable polymers from the medical or consumer industries, which lack the required thermal stability, mechanical strength, and cost-effectiveness, these advanced materials must be formulated from readily available raw materials and manufactured on an industrial scale. Over the past two decades, significant progress has been made in the design and application of polymers like poly(glycolic acid), polyurethane, polyamide, epoxy, and isocyanate ester, developed through collaborative efforts between academia and industry. This review provides a comprehensive overview of the evolution of dissolvable polymer composites, covering material design, degradation mechanisms, manufacturing processes, and field applications. It concludes with insights into future development opportunities in the field. Full article

This study investigates the optimization of airflow distribution and pressure drops in H14 HEPA minipleat filters through the introduction of the hot-melt cell as the fundamental hydraulic unit governing local flow behavior. A coupled analytical framework integrating Falkner–Skan boundary-layer theory, Darcy–Weisbach channel friction, and Darcy porous-medium flow was developed and experimentally tested using velocity measurements obtained in a 600 m³/h test bench operating at a frontal velocity of 0.45 m/s under laminar-flow conditions. Ten primary geometric configurations and 21 hot-melt distribution scenarios (totaling 31 cases plus an optimized design case) were systematically evaluated by varying cell width (W), inlet height (H_i), and pleat length (L). Experimental and analytical results reveal significant velocity heterogeneity in the vicinity of the filter surface, which progressively decreases with distance from the filter, while localized velocity amplification is observed near the hot-melt separators. The analysis demonstrates that hydraulic diameter, pleat angle, and hot-melt spacing are the dominant parameters governing pressure drop generation and flow redistribution. Among the configurations investigated, a model-predicted optimized design (W = 46.25 mm, L = 55.00 mm, 230 pleats) yields a theoretical pressure drop reduction of up to 29.23% without significantly compromising the effective filtration area. These results provide an analytical framework for pre-prototyping optimization, although experimental verification of physical prototype validation for mechanical integrity and the preservation of initial efficiency, among other governing physical quantities, remains essential. The results demonstrate that the proposed hot-melt cell concept provides a practical engineering framework for the aerodynamic optimization of minipleat HEPA filters, enabling improved flow uniformity and reduced energy consumption in cleanroom applications. Full article

Electric pump-fed liquid rocket engines require coordinated propellant delivery under coupled hydraulic, electrical, actuator, and thermal constraints. This study develops an integrated reduced-order model of a dual-channel electric pump-fed propellant system, including the battery and DC bus, power converters, two independently driven motor–pump units, hydraulic feed lines, control valves, combustion chamber, and thermal states. A hierarchical constrained multi-criteria supervisory controller is formulated to regulate chamber pressure, oxidizer-to-fuel mixture ratio, feed-channel coordination, electrical loading, and thermal response. Performance is compared with a conventional PI controller and an enhanced PI configuration incorporating feedforward and disturbance compensation under nominal, degraded, long-duration, and constraint-active scenarios. Relative to the baseline PI controller, the proposed controller reduced the startup pressure peak from 2.64 to 2.32 MPa, pressure RMSE from 0.016 to 0.006 MPa, and mean branch synchronization error from 0.112 to 0.028 MPa. The minimum battery voltage increased from 87.0 to 90.4 V, while the peak motor current decreased from approximately 88 to 65 A. In the 1800 s thermal case, the maximum fuel-drive temperature decreased from approximately 104 to 74 °C. Numerical verification and comparison with published experimental benchmarks supported the physical plausibility and equilibrium-scale behavior of the reduced-order model, while differences in absolute transient time scales limit its use for quantitative prediction of hardware transient dynamics. The results indicate improved coordinated control within the investigated operating envelope and support the use of the framework for comparative system-level assessment and preliminary design of small-class electric-pump propulsion systems. Full article