Search Results (1,649)

This study utilizes the drift–flux model to develop a new flow pattern map designed to facilitate an accurate estimation of gas void fraction (${\alpha }_g$) in vertical upward flow. The map is parameterized by mixture velocity ($u_m$) and gas volumetric quality (${\beta }_g$), integrating transition criteria from the established literature. For applications characterized by significant pressure gradients, such as gas lift, these criteria were reformulated as functions of pressure, enabling direct estimation from operational data. A critical component of this methodology for the estimation of ${\alpha }_g$ is the estimation of the distribution parameter ($C_0$). An analysis of experimental data, spanning pipe diameters from 1.27 to 15 cm across the full void fraction ranges (${0<\alpha }_g<1$), revealed a critical ${\alpha }_g$ threshold beyond which $C_0$ exhibits a distinct decreasing trend. To characterize this phenomenon, the parameter of the distribution-weighted void fraction (${\alpha }_c={\alpha }_g{C}_0$) is introduced. This parameter, representing the dynamically effective void fraction, identifies the critical threshold at its inflection point. The proposed model subsequently defines $C_0$ using a two-part function of ${\alpha }_c$. This generalized approach simplifies the complexity inherent in existing correlations and demonstrates superior predictive accuracy, reducing the average error in ${\alpha }_g$ estimations to 5.4% and outperforming established methods. Furthermore, the model’s parametric architecture is explicitly designed to support the optimization and fine-tuning of coefficients, enabling future use of machine learning for various fluids and complex industrial cases. Full article

In agricultural workplaces, upper-body strain arises not only from lifting and carrying harvest crates but also from pushing, pulling, twisting, and squatting motions. Drawing inspiration from the momentary shoulder contraction and whole-body coordination characteristic of traditional Japanese martial arts, this study proposes a method for “moving efficiently with minimal exertion” across multiple task actions, specifically, lateral pushing, fore-aft pulling, and trunk rotation. Each action is modeled as a control system, and mechanical-engineering simulations are employed to derive optimal muscle-output patterns. Simulation results indicate that peak muscular force can be lowered compared with conventional techniques. A simple physical test rig confirms the load-reduction effect, showing decreases in both perceived exertion and electromyographic activity. These findings offer practical knowledge that can be immediately applied not only to agriculture but also to logistics, nursing care, and other settings involving repetitive handling of heavy objects or machine operations. Full article

Background: In recent years, hyaluronic acid filler for the restoration and increase in buttock volume has been a procedure that has seen increasing success, both thanks to the considerable increase in patient demand and thanks to the improvement of implant techniques and device manufacturing technologies. Aims: The primary objective of this pilot study is to demonstrate the validity of an innovative filler inoculation technique in the upper quadrants of the buttocks and in the supra- and subfascial area in order to optically restore the appearance of a pleasant lumbar lordosis and to lift the upper quadrants with reduction in the infragluteal fold. The secondary objective is to evaluate the safety and efficacy of Sofiderm SubSkin^® (Techderm Biological Products Co., Ltd., Hangzhou, China), a highly versatile hyaluronic acid filler, formulated with a rheology suitable for use on the face and body. Patients/Methods: Five female subjects (50–63 years) were subjected to gluteal fillers in the supra- and subfascial areas; the correct positioning of the filler was investigated by means of a 20 Mhz ultrasound probe. Results: All patients obtained a significant improvement in the projection of the upper part of the buttocks. The implantation technique and the optimal rheological properties of the device brought about a natural and well-defined increase in volume, with a projection of the upper part of the buttocks and a consequent lifting of the lower parts and reduction in the length of the infragluteal fold. Conclusions: This study confirmed the efficacy and safety of the cross-linked hyaluronic acid Sofiderm Derm SubSkin^® in increasing the projection of the upper part of the buttocks, using an innovative mixed implantation technique, in a sample of selected patients. Full article

Strong crosswinds and train–tunnel aerodynamic interactions cause the aerodynamic loads acting on the train body to change more drastically when a high-speed maglev train enters a tunnel. This greatly raises the risk of safety incidents like derailment or overturning. This study employs the FLUENT 2023 R2 computational fluid dynamics simulation software with an overset grid method to numerically investigate the influence patterns of crosswinds on aerodynamic loads and relevant safety issues for a 600 km/h maglev train entering tunnels under various crosswind conditions. The findings show that (1) the marshaling location has a strong correlation with aerodynamic performance. When there is no crosswind, the head vehicle (HV) has the greatest chance of flipping, while the rear vehicle (RV) has the worst lift characteristics. All three vehicles experience significant sudden changes in lateral force coefficients prior to tunnel entry, indicating considerable derailment risks. (2) Aerodynamic loads on the HV show significantly greater sensitivity to crosswind velocity variations compared to the middle vehicle (MV) and RV, with the amplitude reduction in lateral forces in the HV showing approximately linear increase with wind speed. (3) A 50 km/h reduction in train speed decreases the amplitude of change in the lift coefficient and lateral force coefficient by approximately 4.8% and 8.9%, respectively, and the peak overturning moment in open air and tunnel by approximately 11.4% and 15.7%, respectively. These discoveries have both practical value for advancing high-speed maglev networks and theoretical significance for enhancing the safety and reliability of Chinese maglev systems. Full article

Respirable quartz and dust exposures in dusty façade renovation work tasks were investigated. The presumption was that dust-producing work tasks can be performed safely, keeping exposures low, with practical, easily available methods to control dust emissions and exposure. The aim was to identify deficiencies in exposure management and compare exposure limiting methods to find out how to minimize dust emissions and exposures. Average respirable quartz and dust exposures from the 31 work situations, encompassing nine work tasks studied, were 0.082 and 1.3 mg/m³, respectively. Both values exceed the OEL in Finland, pointing to severe deficiencies in managing exposures. All tasks could, however, be executed safely, keeping exposures low. This often required using respirators while working inside façade covers or close to dust emissions. Other key things when planning exposure maintenance were the following: using water sprays and tool-specific exhausts vents; opening façade cover ventilation apertures; ensuring that non-participants in dusty work tasks are not exposed; working upwind from dust emissions; using pre-blended plaster; using grinders with extension handles; replacing diamond saws and angle grinders with hydraulic cutters when dismantling balcony elements; executing façade jackhammering with robots installed on lifting platforms prior to installing scaffolds and façade covers; detaching façade covers from the clean side; and using lifting platforms. Full article

Predicting lift and drag in hydro turbine design is important to optimize its performance. However, it poses significant challenges due to the complexity of fluid dynamics, which is traditionally addressed by Reynolds-Averaged Navier–Stokes equations, which is time-consuming. Moreover, these methods are computationally demanding, making them a costly approach and less efficient for complex turbine designs. Recent advancements in machine learning (ML) offer a promising alternative with reduced computational costs while maintaining accuracy. This paper explores the use of a data-driven ML model for predicting aerodynamic performance, specifically lift and drag, in hydro turbine design. The models were developed from experimental hydro turbine data gathered from various blade designs and flow conditions. CatBoost yielded the highest predictive accuracy among all the models tested. The findings indicate that CatBoost achieved the best predicted accuracy, followed by LGBM, demonstrating the efficacy of machine learning methodologies in modeling hydrodynamic forces in turbine design. Full article

Background/Objectives: The global response to the COVID-19 pandemic included a notable shift in antibiotic prescribing patterns, with use declining and then rising again as restrictions were lifted. In Poland, point-of-care (POC) testing for infections such as influenza A/B, COVID-19, respiratory syncytial virus (RSV), and Group A Streptococcus was widely introduced in primary care in recent years. This study investigates the patterns of oral antibiotic prescription in Poland during the pandemic and post-pandemic periods. Methods: We analyzed Polish National Healthcare Fund data on reimbursed oral antibiotics—Anatomical Therapeutic Chemical (ATC) J01 class—sold between 2019 and 2024. We quantified antibiotic groups by the number of packages sold and individual agents using the defined daily dose per 1000 inhabitants per day (DDD/TID). Results: Total oral antibiotic reimbursements noted a significant fall from 2019 to 2020 (20.9 million vs. 14.5 million packages reimbursed) and subsequently surged from 16.3 million packages in 2021 to 20.9 million in 2024. The most prescribed groups were penicillins (J01C), macrolides (J01F), and other beta-lactams (J01D). Amoxicillin with clavulanic acid was the most commonly used individual antibiotic, with its DDD/TID rising from an average of 2.3 to 2.6 in 2024. Although the use of phenoxymethylpenicillin initially decreased after the introduction of “strep-tests” in 2022 (DID 0.18 in 2023 vs. 0.23 in 2022), it increased again to 0.26 in 2024. Conclusions: Our findings demonstrate a slight continuous increase in oral antibiotic use in Poland, despite the current widespread availability of POC testing. The persistent and growing preference for amoxicillin with clavulanic acid, an agent not typically recommended as first-line treatment for most infections, suggests that antibiotic stewardship efforts need to continue in order to curb inappropriate prescription. Full article

Background: Platelet-rich fibrin (PRF) is an autologous biomaterial utilized as an adjunct in dental implant surgeries owing to its significant biocompatibility, supra-physiological concentration of growth factors, and ability to speed either soft or hard tissue regeneration. Methods: Today, PRF is available in both solid and liquid forms with an average resorption period of roughly 2 weeks. While various research endeavors have attempted to utilize Solid-PRF as a barrier membrane in guided bone regeneration (GBR) and various other applications, its two-week resorption period has limited its use as a solo “barrier” membrane owing to its faster-than-ideal resorption properties. Results: Recent studies have demonstrated that by heating and denaturing Liquid-PRF/albumin, the resorption properties of the heated albumin gel could be extended from 2 weeks to 4–6 months by utilizing the Bio-Heat technology. This emerging technology was given the working name ‘extended-PRF’ or e-PRF, with many clinical indications being proposed for further study. Numerous clinicians have now utilized extended-PRF (e-PRF) membranes as a substitute for collagen barrier membranes in various clinical applications, such as guided tissue/bone regeneration, recession coverage, and lateral window sinus lifts. Conclusions: This two-part case series paper aims to first illustrate the evolution of techniques developed taking advantage of this new technology in clinical practice for alveolar ridge preservation. This includes four different methods of fabrication of e-PRF along with its application in clinical practice. This article discusses the clinical outcomes, including the advantages/disadvantages of utilizing each of the four separate techniques to prepare and utilize e-PRF membranes for ridge preservation. Full article

Facial asymmetry significantly affects aesthetic appearance, essential functions such as mastication and speech, and psychological well-being. While traditional surgical interventions effectively address significant facial asymmetry, they are often associated with considerable morbidity, prolonged recovery periods, and potential complications. Consequently, interest in minimally invasive, non-surgical techniques has substantially increased, driven by advantages including reduced downtime, rapid recovery, and immediate aesthetic results. This narrative review critically evaluates contemporary non-surgical techniques for correcting facial asymmetry, focusing specifically on dermal fillers, collagen stimulators (polydioxanone powder), polydioxanone thread lifting, energy-based non-invasive devices (radiofrequency, ultrasound, and laser therapies), and extracorporeal shockwave therapy. The review is based on a structured literature search of PubMed/MEDLINE, Embase, and Google Scholar up to October 2025, focusing on human clinical studies and review articles on non-surgical correction of facial asymmetry and related facial contouring. We provide a detailed analysis of each treatment modality’s underlying mechanisms, clinical efficacy, advantages, limitations, and safety profiles. Current evidence suggests that these non-surgical methods effectively enhance facial symmetry by offering immediate visible improvements and progressive enhancements through natural collagen regeneration, thereby significantly improving patient satisfaction and overall quality of life. Clinicians are encouraged to incorporate these versatile, minimally invasive interventions into clinical practice, carefully tailoring treatments according to individual patient characteristics and specific aesthetic goals. Further research should aim to refine existing treatment protocols, evaluate long-term efficacy and safety, and establish standardized guidelines to optimize outcomes in facial asymmetry correction. Full article

The increasing size and weight of deep-water topside modules necessitate reliable and efficient installation methods. The twin-barge float-over technique presents a viable alternative to conventional heavy-lift operations; however, its critical tri-vessel load transfer phase involves complex hydrodynamic interactions and continuous load redistribution that are not adequately captured by traditional staged analyses. This study develops a fully coupled time-domain dynamic model to simulate this process. The framework integrates multi-body potential flow hydrodynamics, mooring and fender systems, and Deck Support Units (DSUs). A novel continuous mass-point variation method is introduced to replicate progressive ballasting and the dynamic load transfer from single- to dual-barge support. Numerical simulations under representative sea states reveal significant narrow-gap resonance effects, direction-dependent motion amplification, and transient DSU load peaks that are overlooked in conventional quasi-static approaches. Beam-sea conditions are found to induce the largest lateral DSU loads and the highest risk of barge misalignment. The proposed framework demonstrates superior capability in predicting motion responses and load transitions, thereby providing critical technical support for the safe and efficient application of twin-barge float-over installations in complex marine environments. Full article

Shaft lifting is an important process of coal mining, and its integrity is a prerequisite for ensuring efficient mining. The non-mining-induced rupture of vertical shafts in coal mines, primarily caused by the consolidation settlement of overlying unconsolidated strata due to aquifer dewatering, poses a significant threat to mining safety. Accurately predicting such ruptures remains challenging due to the multicollinearity and complex interactions among multiple influencing factors. This study proposes a novel multiscale discriminant analysis model, termed the SDA-PCA-FDA model, which integrates Stepwise Discriminant Analysis (SDA), Principal Component Analysis (PCA), and Fisher’s Discriminant Analysis (FDA). Initially, SDA screened five principal controlling factors from nine original variables. Subsequently, PCA was applied to reorganize these factors into three principal components, effectively eliminating information redundancy. Finally, the FDA model was established based on these components. Validation results demonstrated that the SDA-PCA-FDA model achieved high correct classification rates of 96.43% and 91.67% on the training and testing sets, respectively, significantly outperforming traditional FDA, PCA-FDA, and SDA-FDA models. Applied to engineering practice in the Yanzhou Mining Area, the model successfully predicted the rupture risk of the main shaft, consistent with field observations. Furthermore, to achieve sustainable governance, the “Friction Pile Method” was proposed as a preventive measure. Numerical simulations using NM2dc software determined the optimal governance parameters: a pile height of 112.86 m, a stiffness coefficient of 0.9, and a pile–shaft spacing of 10 m. A comparative analysis incorporating techno-economic sustainability indicators confirmed the superior effectiveness and economic viability of the friction pile method over traditional approaches. This research provides a reliable, multiscale methodology for both the prediction and sustainable governance of non-mining-induced shaft rupture. Full article

Unmanned aerial vehicles (UAVs) are regarded as a novel mode for urban air mobility, earning increasing attention on many commercial and civil applications. The risk of UAVs to people on the ground is heightened by airspace range and operational risks, and the quantitative ground risk buffer estimation are highly required to protect the people on the ground. In this work, a ground risk buffer estimation method based on the analysis of the UAVs dynamics is proposed. It is a 3D contour map, incorporated with flight test parameters, to determine the ground risk buffer for both, rotorcraft UAVs and fixed-wing UAVs. The contour map is generated through UAVs dynamics analysis and combines several parameter layers, including altitude and speed at moment of failure occurence, environment conditions and the lift-to-drag ratio. Each location of the map has associated a value that quantifies the area of the ground risk buffer for a specific test flight condition. The ground risk buffer determined by the current Specific Operations Risk Assessment framework using the 1-to-1 principle is provided for comparison. The proposed method exhibits greater safety margin and further proves the potential of the new estimation method in the perspective of risk quantification and practical engineering applications. Full article

The parametric design of a low-power (<1 kW) H-type vertical-axis wind turbine tailored to the wind conditions of the Yucatán Peninsula is presented. Nine airfoils were evaluated using the Double Multiple Streamtube method and Qblade Lifting-Line Theory numerical simulations, considering variations in solidity (σ = 0.20–0.30), aspect ratio (A_r = H/R = 2.6–3.0), number of blades (2–5), and a swept-area constraint of 4 m². The parametric study shows that fewer blades increase Cp, although a three-blade rotor improves start-up torque, vibration mitigation, and load smoothing. The recommended configuration—three blades, A_r = 2.6, σ = 0.30 and S1046 (or NACA 0018) operated near λ ≈ 3.75—balances efficiency and start-up performance. For the representative mean wind velocity of 5 m/s, typical of the Yucatán Peninsula, the VAWT achieves a maximum output of 136 W at 220 rpm. Under higher-wind conditions observed in specific sites within the region, the predicted maximum output increases to 932 W at 380 rpm. Full article

Advances in distributed electric propulsion and urban air mobility technologies have spurred a surge of research on electric Vertical Take-Off and Landing (eVTOL) aircraft. Distributed Multi-Propeller Tilting-Wing (DMT) eVTOL configurations offer higher forward flight speed and efficiency. However, aerodynamic challenges during the transition phase have limited their practical application. This study develops a high-fidelity body-fitted mesh CFD numerical simulation method for flow field calculations of DMT aircraft. Using the reverse overset assembly method and CPU-GPU collaborative acceleration technology, the accuracy and efficiency of flow field simulations are enhanced. Using the established method, the influence of dynamic tilting speeds on the flow field of this configuration is investigated. This paper presents the variations in the aerodynamic characteristics of the tandem propellers and tilt-wings throughout the full tilt process under different tilting speeds, analyzes the mechanisms behind reductions in the propeller’s aerodynamic performance and tilt-wing lift overshoot, and conducts a detailed comparison of flow field distribution characteristics under fixed-angle tilting, slow tilting, and fast tilting conditions. The study explores the influence mechanism of tilting speed on blade tip vortex-lifting surface interactions and interference between tandem propellers and tilt-wings, providing valuable conclusions for the aerodynamic design and safe transition implementation of DMT aircraft. Full article

Background: With the development of wireless communication technologies, the rapid advancement of 5G and 6G communication systems has spawned an urgent demand for low latency and high data rates. Orthogonal Frequency Division Multiplexing (OFDM) communication using high-order digital modulation has become a key technology due to its characteristics, such as high reliability, high data rate, and low latency, and has been widely applied in various fields. As a component of cognitive radios, automatic modulation classification (AMC) plays an important role in remote sensing and electromagnetic spectrum sensing. However, under current complex channel conditions, there are issues such as low signal-to-noise ratio (SNR), Doppler frequency shift, and multipath propagation. Methods: Coupled with the inherent problem of indistinct characteristics in high-order modulation, these currently make it difficult for AMC to focus on OFDM and high-order digital modulation. Existing methods are mainly based on a single model-driven approach or data-driven approach. The Adaptive Wavelet Mamba Network (AWMN) proposed in this paper attempts to combine model-driven adaptive wavelet transform feature extraction with the Mamba deep learning architecture. A module based on the lifting wavelet scheme effectively captures discriminative time–frequency features using learnable operations. Meanwhile, a Mamba network constructed based on the State Space Model (SSM) can capture long-term temporal dependencies. This network realizes a combination of model-driven and data-driven methods. Results: Tests conducted on public datasets and a custom-built real-time received OFDM dataset show that the proposed AWMN achieves a performance reaching higher accuracies of 62.39%, 64.50%, and 74.95% on the public Rml2016(a) and Rml2016(b) datasets and our formulated EVAS dataset, while maintaining a compact parameter size of 0.44 M. Conclusions: These results highlight its potential for improving the automatic modulation classification of high-order OFDM modulation in 5G/6G systems. Full article