Search Results (3,641)

Punch-through accidents pose a significant risk during the positioning of jack-up rigs. To mitigate this hazard, accurate prediction of the peak penetration resistance of spudcan foundations is essential for developing safe operational plans. Advances in artificial intelligence have spurred the widespread application of machine learning (ML) to geotechnical engineering. To evaluate the prediction effect of different algorithm frameworks on the peak resistance of spudcans, this study evaluates the feasibility of ML and multi-view learning (MVL) methods using existing centrifuge test data. Six ML models—Random Forest, Support Vector Machine (with Gauss, second-degree, and third-degree polynomial kernels), Multiple Linear Regression, and Neural Networks—alongside a Ridge Regression-based MVL method are employed. The performance of these models is rigorously assessed through training and testing across various working conditions. The results indicate that well-trained ML and MVL models achieve accurate predictions for both sand-over-clay and three-layer clay strata. For the sand-over-clay stratum, the mean relative error (MRE) across the 58-case dataset is approximately 15%. The Neural Network and MVL method demonstrate the highest accuracy. This study provides a viable and effective empirical solution for predicting spudcan peak resistance and offers practical guidance for algorithm selection in different stratigraphic conditions, ultimately supporting enhanced safety planning for jack-up rig operations. Full article

This study aimed to synthesize a magnetic biochar@ZIF-8 composite derived from almond shell biomass for the adsorption of fluoroquinolones (FQs) from aqueous media. The biochar was prepared under different pyrolysis conditions using a central composite design (CCD) based on temperature and residence time, with biochar yield (%) and ofloxacin adsorption capacity selected as the response variables. Subsequently, the composite was obtained by combining KOH-activated biochar with ZIF-8 and magnetic particles, producing a hierarchically porous material with enhanced surface area and functional groups favorable for adsorption. The physicochemical and morphological properties of the composite were characterized by SEM–EDS, FTIR, BET, TGA, and XRD analyses, confirming the successful incorporation of ZIF-8 and magnetic phases onto the biochar surface. The adsorption performance was systematically evaluated by studying the effects of pH and contact time. The kinetic data fitted well to the pseudo-second-order model, suggesting that chemisorption predominates through π–π stacking, hydrogen bonding, and coordination interactions between FQ molecules and the active sites of the composite. Furthermore, the material exhibited high reusability, maintaining over 84% of its adsorption capacity after four cycles, with efficient magnetic recovery without the need for filtration or centrifugation. Overall, the magnetic biochar@ZIF-8 composite demonstrates a sustainable, cost-effective, and magnetically separable adsorbent for water remediation, transforming almond shell waste into a high-value material within the framework of circular economy principles. Full article

Dewatering of sewage sludge is a key operational element of wastewater treatment plants and has major economic implications, as it entails the costs of thickening, transport, and disposal. The aim of this study was to determine the influence of selected polyelectrolytes and their dosages on dewatering efficiency and to present an innovative, multicriteria method of result evaluation using radar charts. In this research, 10 different polyelectrolytes were assessed in terms of sludge dewaterability, considering conditioning parameters including Specific Resistance to Filtration (SRF), Capillary Suction Time (CST), and centrifugation performance. The results were presented in the form of radar charts, enabling both an overall evaluation of the effectiveness of each product and an assessment of their suitability for specific dewatering technologies, such as belt filter presses and centrifuges. The analysis showed that polyelectrolytes with higher cationic charge provided better dewatering performance. The proposed visualization method allows us to analyze the effects across different conditioners and technologies. The best sludge conditioning effect (maximum radar chart area) was achieved with Praestol 665, a polyelectrolyte with a high cationic charge level. This method is a practical tool for selecting the optimal agent for sewage sludge dewatering. Full article

The irreducible water saturation of reservoirs seriously restricts the efficient drainage of unconventional energy sources. NMR logging can be used to determine parameters such as total porosity, effective porosity, irreducible water saturation, and permeability, which play an important role in oil and gas identification. T_{2 cut off} value identification using the NMR T₂ spectrum is the key to clarifying the irreducible water saturation of unconventional reservoirs. In this paper, saturation and centrifugal T₂ spectra of sandstone and coal samples are used to study and calculate the T_{2 cut off} value, with methods including single fractal dimension, multi-fractal dimension, and spectrum morphological discrimination; in addition, the applicability of these three methods in characterizing T_{2 cut off} is discussed. According to the morphological difference of the saturated T₂ spectrum, relationships between morphological parameters and the T_{2 cut off} of four types of sample are described. The parameters related to T_{2 cut off} can be divided into two types: (1) the first type includes morphological parameters main peak position (T_M) and smaller-pore volume percentage (SPVP); with an increase of T_{2 cut off}, T_M increases linearly and SPVP decreases exponentially, and the correlation between SPVP and T_{2 cut off} is stronger than that of T_M. (2) The other type includes fractal parameters D₂ (fractal dimension of larger pore), D₋₁₀ – D₁₀, and D₋₁₀/D₁₀; with the increase of T_{2 cut off}, single and multi-fractal dimensions all increase linearly, and the correlation between D₂ and T_{2 cut off} is stronger than that of the multi-fractal dimension. When calculating the T_{2 cut off} of samples with macro-pores developed, spectrum morphological methods should be used preferentially, while the fractal dimension discrimination methods need be used for the T_{2 cut off} of samples with developed micro-pores. Then, the T_{2 cut off} value prediction and evaluation system are described. The overall results of this work can provide a theoretical basis for the inversion of bound water content in the original formation. Full article

This review aims to provide a complete and comprehensive state of the art of the SCOSSA computer code, which is a one-dimensional nonlinear computer code used for the analysis of seismic site response and soil instability. Indeed, among the effects of earthquakes, the activation of landslides and liquefaction constitute two of the predominant causes of vulnerability in the physical and built environment. The SCOSSA computer code (Seismic Code for Stick–Slip Analysis) was initially developed to evaluate the permanent displacements of simplified slopes using a coupled model, and introduced several improvements with respect to the past, namely, the formulation for solving the dynamic equilibrium equations incorporates the capability for automated detection of the critical sliding surface; an up-to-date constitutive model to represent hysteretic material behavior and a stable iterative algorithm to support the solution of the system in terms of kinematic variables. To address liquefaction-induced failure, a simplified pore water pressure generation model was subsequently developed and integrated into the code, coupled with one-dimensional consolidation theory. This review retraces the main features, developments, and applications of the computer code from the origin to the present version. Full article

The efficiency of centrifugal pumps is strongly influenced by impeller blade design; however, studies on double-curvature impellers remain limited. This research evaluates the impact of double-curvature impellers on pump performance through experimental measurements. Five impeller configurations were tested experimentally, and their hydraulic behavior was analyzed at three rotational speeds: 1400, 1700, and 1900 rpm. For each impeller–speed combination, 12 measurement points were recorded, capturing suction and discharge pressures, flow rate, rotational velocity, electrical parameters, and power consumption. Additionally, four impellers with double-curvature designs of 15%, 25%, and 35% were developed to improve flow guidance between blades and enhance the hydraulic performance of the pump. Quantitatively, the double-curvature impellers demonstrated performance improvements over the baseline configuration, achieving increases in hydraulic head of approximately 5–10% and peak efficiency gains of 4–8 percentage points (equivalent to 10–18% relative improvement), particularly in mid-range flow conditions. These enhancements confirm the beneficial role of blade double curvature in reducing internal losses and improving flow guidance. The results were used to derive head–flow and efficiency–flow relationships, demonstrating that specific double-curvature configurations can enhance pump performance compared to the original design. Full article

Plasma separation is an essential step in blood-based diagnostics. While traditional centrifugation is effective, it is costly and usually restricted to centralized laboratories because it requires relatively expensive equipment, a supply of consumables, and trained personnel. In an effort to alleviate these shortcomings, microfluidic and point-of-care devices offering rapid and low-cost plasma separation from small sample volumes, such as finger-stick samples, are quickly emerging as an alternative. Such microscale plasma separation systems enable reduced costs, rapid test results, self-testing, and broader accessibility, particularly in resource-limited or remote settings and facilitate the integration of separation, fluid handling, and downstream analysis into portable, automated lab-on-a-chip platforms. This review highlights advances in microfluidic systems and lab-on-a-chip devices for plasma separation categorized in design strategies, separation principles and characteristics, application purposes, and future directions for the decentralization of healthcare and personalized medicine. Full article

Three-wheeled vehicles are gaining popularity in European and Asian cities due to their low cost, stability, maneuverability, and compact size. Among these, tilting vehicles facilitate cornering, maintain stability, and reduce centrifugal forces. This study investigates a delta-configured, three-wheeled tilting vehicle designed for people with reduced mobility. Vehicle dynamics were analyzed using ADAMS/Car simulations, including steady-state cornering and single-lane change tests, focusing on body motion and forces in suspension and steering systems. Results show that tilting of the body significantly enhances cornering safety compared to non-tilting three-wheelers, providing insights for designing efficient urban vehicles for diverse user groups. Full article

Biomimetic scaffolds are required in tissue engineering to provide structural support as well as promote cell adhesion, proliferation, and differentiation. Fibrous scaffolds composed of micro- and nanofibers replicate the architecture of the native extracellular matrix. Electrospinning is widely used for fabricating nanofibers; however, constructing fibrous scaffolds that integrate multiple fiber scales into a single structure is difficult. We addressed this issue by developing a fiber-spinning device using two pairs of counter-facing syringes that simultaneously produce micro- and nanofibers under different processing conditions. Poly(ε-caprolactone) solutions are ejected through needle-type nozzles via centrifugal force, and fiber diameter is controlled by adjusting the polymer concentration and nozzle diameter. We fabricated scaffolds with the proposed device, which exhibited a random three-dimensional fibrous network in which microfibers and nanofibers were homogeneously integrated. C2C12 myoblasts cultured on the composite scaffolds strongly adhered to the fibrous network, remained viable, and extended along the fibers to form multinucleated cells within the structure. The developed system produced composite micro/nanofiber scaffolds with tunable morphology and biocompatibility, providing a platform for fibrous tissue engineering applications. Full article

To promote domestic wheat production in South Korea, four functional colored wheat varieties with varying amylose contents: Ariheuk (AH), Arijinheuk (AJ), Ariheukchal (AC), and Sintong (ST), were developed. This study examined their bread-making performance using whole wheat flour (WWF) milled under different conditions with an ultra-centrifugal mill (sieve openings: 0.5 and 1.0 mm; rotation speeds: 6000 and 14,000 rpm). Four flour samples per variety (FL, FH, CL, CH) were prepared. The median particle size (d50) varied among varieties, with harder kernels (AC, AH) producing larger particles than softer ones (AJ, ST). Smaller sieve openings increased the water and sodium carbonate solvent retention capacity, whereas higher rotation speeds reduced them, indicating less damaged starch. Sodium dodecyl sulfate sedimentation volume was higher in AC and AH, suggesting stronger gluten. Bread made from the group F WWF had higher volume and lower firmness, with AH-FH producing the best bread quality. Total phenolic and anthocyanin content and antioxidant activity were slightly higher in the group F, but markedly lower in the ST. Bread crusts showed increased phenolic and antioxidant activity but decreased anthocyanin content due to heat. Overall, kernel hardness, milling conditions, and amylose content strongly influenced purple WWF quality and bread performance, highlighting the need to optimize milling and formulation strategies. Full article

This paper addresses the problem of high fine particle content in the overflow and insufficient separation efficiency of traditional cyclone clarifiers. A cyclone clarifier with a spiral guide groove is proposed. A comparative numerical simulation analyzes the flow field characteristics and separation performance inside traditional and spiral guide groove cyclone clarifiers. Comparing the flow fields shows that the spiral guide groove increases tangential velocity at the inlet, centrifugal force increases, axial velocity decreases, separation time increases, and separation efficiency improves. The spiral guide groove forces the fluid to follow an optimized path. It reduces circulating flows and vortices. The flow field becomes more uniform and stable. In the cone-plate region, streamlines are dense and axial velocity is low. This favors particle settling. In the underflow region, turbulent kinetic energy and the interaction between inner and outer vortices decrease. This reduces the number of particles entering the overflow pipe with the inner vortex. Compared to the traditional cyclone clarifier, the spiral guide groove cyclone clarifier effectively improves particle removal efficiency. The removal efficiency increases by 6.8%. The improvement effect varies for different particle sizes. The removal efficiency improvement is greatest for 15–20 μm particles. It effectively improves the water quality of the overflow outlet. Full article

Centrifugal compressors are vital components in industrial applications, but they are prone to a disruptive phenomenon known as surge, which can lead to mechanical stress and temperature increase. Surge occurrence is influenced by machine design, plant layout, and geometry. Engineers often deploy long (cold) and short (hot) recycle valves to address this issue. To ensure surge prevention, a fluid dynamic model is indispensable. In this study, a 1D Computational Fluid Dynamics (1D-CFD) model was developed using Amesim for a two-section centrifugal compressor. The main objective was to investigate the impact of various parameters on surge occurrence and compare different plant layouts to determine the most suitable solution for the specific study case. Here, the focus is on the influence of vent valves over the plant performance. To achieve this comparison, transient simulations of emergency shutdown (ESD) operations were performed. This study contributes to a better understanding of how machine design and operational factors affect surge behavior. By systematically evaluating different plant layouts, we identified the most effective strategies for preventing surge and enhancing compressor performance. This research provides valuable insights for engineers and operators striving to optimize industrial processes and improve the reliability and efficiency of centrifugal compressor systems. Full article

This study investigates the correlation between strains obtained from the image-based technique GeoPIV and Fiber Bragg Grating (FBG) sensors’ measurements in Mechanically Stabilized Earth (MSE) systems, using scaled physical modeling in a geotechnical centrifuge. FBG sensors provide high-resolution, localized strain data along reinforcements, while GeoPIV offers full-field visualization of soil deformation. By calibrating GeoPIV outputs to microstrains, the complementary strengths of the two approaches are highlighted. In addition, the centrifuge setup reproduces realistic stress conditions, enhancing experimental reliability. The combined use of these methods not only improves understanding and monitoring of MSE behavior but also demonstrates strong potential for broader application in other laboratory-scale studies. Full article

Designed to mitigate the significant low-frequency vibration and noise inherent in conventional marine centrifugal pump systems, the magnetic levitation pump constitutes a novel form of centrifugal pump employing active magnetic bearing technology. While this fully levitated design effectively enhances vibration and noise performance, it results in the complete immersion of the rotor within a confined fluid domain, which contains narrow fluid clearances. This poses significant challenges for the accurate computation of rotor wet modes, which is crucial for the structural design of the rotor system to avoid the resonance induced by flow. Despite exerting a substantially greater influence on rotor wet modal characteristics than unconfined domains, the analysis of rotors under confined fluid conditions has received comparatively little research attention. This study focuses on two types of magnetic levitation pump rotors. From the perspective of analytical modeling, an improved analytical method for wet modal computation based on added mass correction is proposed. The validation of this method included examining two distinct computational approaches for the added mass, the thickening treatment for axially elongated disk components, and the methodology for implementing disk equivalent density. Based on this foundation, wet modal analysis was performed on both rotors utilizing the proposed analytical method, alongside acoustic fluid–structure interaction simulations. The results indicate that for the first bending mode, the errors between the analytical and experimental values are 1.2% and 4.1%, respectively, while the discrepancies between the simulated and experimental values are 0.1% and 3.2%. Finally, regularity analysis was conducted on the wet modal characteristics of the rotor under confined water, considering various fluid clearances. The results reveal that the first three bending modes generally exhibit an increasing trend with the enlargement of the fluid clearance, with a triple-size annulus serving as a transition point. However, increasing the annulus size does not always elevate the modal frequencies above their initial values. This study contributes to understanding the influence mechanisms of confined water on the wet modal properties of magnetic levitation pump rotors. Furthermore, the proposed analytical method improved computational efficiency for the early design stages of water-immersed rotors, alongside a model of greater accuracy essential for magnetic bearing control. Full article

The current work highlights key challenges in the design of small-scale, high-rotational-speed centrifugal compressors for R-290 at domestic application scale on the basis of a single-stage demonstrator unit that is currently developed by ebm-papst. The demonstrator is operated in a vapor-compression cycle at a total pressure ratio up to 3, a maximum rotational speed of 240 krpm, and with maximum power supply of 3.2 kWe. Emphasis is placed on challenges related to aerodynamic stage design, impeller back wall sealing, and impeller thrust force balancing. Appropriate measures are proposed to overcome these challenges and compressor performance is quantified to evaluate the prospects of small-scale, centrifugal compressors for R-290 application in a wider context. Considerations related to mechanical design and manufacturing are briefly illustrated. Main design and performance assessments are conducted through 3D CFD RANS calculations. Full article