Search Results (929)

As global Marine resource development continues to expand into deep-sea and ultra-deep-sea domains, the intelligent and green transformation of deep-sea aquaculture equipment has become a key direction for high-quality development of the Marine economy. Large deep-sea cages are considered essential equipment for deep-sea aquaculture. However, there are significant challenges associated with ensuring their structural integrity and long-term monitoring capabilities in the complex Marine environments characteristic of deep-sea aquaculture. The present study focuses on large deep-sea cages, addressing their dynamic response challenges and long-term monitoring power supply needs in complex Marine environments. The present study investigates the nonlinear vibration characteristics of flexible net structures under complex fluid loads. To this end, a multi-field coupled dynamic model is constructed to reveal vibration response patterns and instability mechanisms. A self-powered sensing system based on triboelectric nanogenerator (TENG) technology has been developed, featuring a curved surface adaptive TENG array for the real-time monitoring of net vibration states. This review aims to focus on the research of optimizing the design of curved surface adaptive TENG arrays and deep-sea cage monitoring. The present study will investigate the mechanisms of energy transfer and cooperative capture within multi-body coupled cage systems. In addition, the biomechanics of fish–cage flow field interactions and micro-energy capture technologies will be examined. By integrating different disciplinary perspectives and adopting innovative approaches, this work aims to break through key technical bottlenecks, thereby laying the necessary theoretical and technical foundations for optimizing the design and safe operation of large deep-sea cages. Full article

The radius-to-width ratio has an obvious impact on the flow structure within curved channels, which most natural rivers possess, but there are currently few studies on the influence of the radius-to-width ratio of a tributary (R/B) on the hydrodynamic characteristics of a confluent channel. In order to contribute to this field of research, this study employed the RNG k-ε turbulence model, which has good applicability and accuracy for confluence, to investigate the effects of the R/B and flow ratios (q*) on the hydraulic characteristics of confluence. The results reveal that the numerical model can effectively simulate the velocity distribution in the confluence. The values of the key errors are all relatively small (e.g., the value of Mean RMSE is 0.05), and the flow patterns near the bed and water surfaces are different. The maximum velocity zone (MVZ) and the scale of the separation zone (SZ) increase as R/B increases; conversely, the MVZ and the scale of the SZ decrease as the q* increases. Upstream of the confluence, turbulent kinetic energy (TKE) increases and decreases as R/B and q* increase, respectively, while TKE downstream of the confluence hardly changes. Furthermore, the size of the SF decreases as R/B increases. The value of $\overline{S_w}$ peaks downstream of the confluence, increases with the increase in the R/B, and decreases with the increase in the q*. The results of this study will contribute to a better understanding of the hydrodynamic characteristics of confluence and provide valuable insights for the management and ecological restoration of confluent channels. Full article

Background: As an extremely sensitive organ, particularly during in utero development, the brain has intrinsic systems to reduce the risk of cerebral damage in cases of insult, such as energy deprivation, due to a mechanism of positive balance in cerebral oxygen–energy substrate demand and supply. This mechanism is called cerebral autoregulation and is present in both the fetal and adult brain. The inaccessibility of the fetal brain to currently available measurement techniques limits its knowledge. Physiological and pathological alterations of fetal cerebral blood flow (CBF) can be assessed during the latter half of pregnancy using sonographic Doppler studies. The limited studies on this subject suggest a potential role for Doppler assessment of the fetal internal carotid artery. Objective: This article reviews the concept of CBF autoregulation and the role of fetal Doppler studies in various brain vascular territories in clinical practice. Methods: A PubMed search was performed, and 156 English articles were used as references in this bibliographic review, published between January 1996 and December 2021. Results: The study of fetal CBF involves indirect observation; the fetal brain constantly changes its characteristics towards complete maturation, which will be fully accomplished only after birth, and the maternal environment influences this process. Conclusions: Doppler study of the internal cerebral artery might be useful in clinical practice. However, technical issues for its study are not established, there are no reference curves, and studies on its clinical value have limited applicability. Full article

Based on the high strength and superior deformation control capabilities of rock strata, a novel cantilever anti-floating ledge has been proposed to resist the floating of underground structures in rock strata. To explore the actual anti-floating effect and working performance of the structure, laboratory shear tests were designed based on the actual project. The shear characteristics and failure evolution process were then discussed using the Particle Flow Code (PFC) numerical simulation. The main conclusions are as follows. The shear stress–shear displacement curve of the cantilever anti-floating ledge can be described as six stages according to the different states of stress and deformation. With the increase in groundwater buoyancy, the damage to the cantilever anti-floating ledge occurs successively from the ledge, the concrete–rock interface, the connection between the ledge and the side wall, and the connection between the ledge and the bottom plate. Local damage and delamination of the interface do not affect the structural strength, but structural cracks should be prevented from continuing to form and connect. It is necessary to pay attention to the stress and deformation state of the crack-prone area mentioned above, improve the reinforcement ratio in the crack-prone area, and strengthen the bond between the concrete and the rock. Full article

Soil desiccation cracks are common in farmland under dry conditions, which can alter soil water movement by providing preferential flow paths and thus affect water and fertilizer use efficiency. Understanding the mechanism of soil shrinkage and cracking is of great significance for optimizing field management by crack utilization or prevention. The behavior of soil shrinkage and cracking was monitored during drying experiments and analyzed with the help of a digital image processing method. The results showed that during shrinkage, the changes in soil height and equivalent diameter with water content differed significantly. The height change consisted of a rapid decline stage and a residual stage, while the equivalent diameter had a stable stage before the rapid decline stage. The VG-Peng model was suitable to fit the soil shrinkage characteristic curves, and the curves revealed that the soil shrinkage contained structural shrinkage, proportional shrinkage, residual shrinkage, and zero shrinkage stages. According to the changes in evaporation intensity, soil water evaporation could be divided into three stages: stable stage, declining stage, and residual stage. Cracks first formed in the defect areas and edge areas of the soil, and they mainly propagated in the stable evaporation stage. Crack development was dominated by an increase in crack length during the early cracking stage, while the propagation of crack width played a major role during the later stage. At the end of drying, the contribution ratio of crack length and width to the crack area was approximately 30% and 70%, respectively. The box-counting fractal dimension of the stabilized cracks was approximately 1.65, indicating that the crack network had significant self-similarity. The experimental results were used to implement the discrete element method to model the process of soil shrinkage and cracking. The models could effectively simulate the variation characteristics of soil height and equivalent diameter during shrinkage, as well as the variation characteristics of crack ratio and length density during cracking, with acceptable relative errors. In particular, the modeled morphology of the crack network was highly similar to the experimental observation. Our results provide new insights into the characterization and simulation of soil desiccation cracks, which will be conducive to understanding crack evolution and soil water movement in farmland. Full article

Background/Objectives: A variant of autism spectrum disorder (ASD) known as Asperger syndrome (AS) shows increasing incidence worldwide, affecting between 0.02% and 0.03% of children. Patients display abnormal conduct, are limited in social interaction and communication, and are more often affected by micturition disorders, incontinence, and voiding symptoms than typically developing children. Methods: The present study aimed to review the literature related to the current management of lower urinary tract conditions in children with Asperger syndrome and to present a case of a 14-year-old girl with ASD, with characteristic impairments, including communication challenges, stereotyped, repetitive behaviors, and chronic constipation with concomitant bladder dysfunction, presenting recurrent urinary tract infections (UTIs) and lower urinary tract symptoms (LUTS), including voiding and filling storage symptoms. For the AS, she was treated with a selective serotonin reuptake inhibitor (Sertraline). An abdominal ultrasound, PLUTTS—pediatric lower urinary symptoms scoring (21); QL-quality of life (3); voiding diary; and uroflowmetry were performed, revealing an incomplete urinary retention (incomplete bladder emptying of 120 mL), a prolonged and interrupted curve, a maximum urinary flow rate (Qmax) 7 mL/s, and a UTI with Enterococcus. Results: Besides psychiatric reevaluation and antibiotic therapy, functional magnetic stimulation (FMS) sessions were performed. After eight sessions (20 min, 35 MHz, every second day), the ultrasound control and the uroflowmetry showed no residual urine, and the Qmax was 17 mL/s. The curve continued to be interrupted: PLUTSS-11, QL-1. FMS was continued at two sessions per week. At the 3-month follow-up, no residual urine was detected, and Qmax reached 24 mL/s. Conclusions: ASD is an incapacitating/debilitating condition that significantly impairs social functioning. In many cases, in addition to psychological symptoms, other conditions such as LUTS and constipation may coexist. Antipsychotics and antidepressants are frequently prescribed for these patients, often leading to various side effects, including micturition disorders. Therefore, screening for LUTS is recommended, and, if indicated, treatment—especially non-pharmacological and non-invasive approaches, such as FMS—should be considered. Full article

Background: Glaucoma is a multifactorial optic neuropathy and the leading cause of irreversible blindness worldwide. Vascular mechanisms, including impaired perfusion of the optic nerve head, are increasingly recognized as contributors to disease progression. Optical coherence tomography angiography (OCTA) enables non-invasive assessment of retinal and choroidal microvasculature, including peripapillary microvasculature dropout (MvD), which may serve as a marker of glaucomatous damage. Methods: A cross-sectional case–control study was conducted, including patients with primary open-angle glaucoma (OAG) and healthy controls. All participants underwent a comprehensive ophthalmic evaluation and OCTA imaging using the PLEX Elite 9000 system. Peripapillary vessel density (pVD), flow index (pFI), peripapillary choroidal thickness (PCT), β-zone parapapillary atrophy (β-PPA), and choroidal vascular indices were measured. MvD was defined as the complete absence of microvasculature within the β-PPA boundary. Statistical analyses included univariate and multivariate regression models to examine variables associated with PCT and to assess the association between MvD and visual field mean defect (MD), as well as other glaucoma characteristics. ROC curve analysis was performed to evaluate the ability of MvD to discriminate between different levels of visual field defects. Results: A total of 87 eyes (41 glaucomatous, 46 controls) were analyzed. Glaucoma patients exhibited significantly lower pVD, pFI, PCT, and choroidal vascular indices compared to the controls. MvD was detected in 10 glaucomatous eyes and was associated with a larger β-PPA area, smaller choroidal luminal and stromal areas, and worse mean deviation (MD) values. Multivariate regression showed that the number of ocular hypotensive treatments and StructureIndex variables were significantly associated with PCT (adjusted R² = 0.14). Logistic regression analysis identified MD, MD slope, and β-PPA area as variables significantly associated with the presence of MvD. ROC analysis showed that the presence of MvD had good discriminatory ability for visual field mean defects (MDs) (AUC = 0.77, 95% CI: 0.69–0.87; p = 0.005). Conclusions: Peripapillary MvD detected by OCTA is associated with reduced choroidal vascularity, increased β-PPA, and greater visual field deterioration in glaucoma patients. MvD may serve as a structural marker associated with functional deterioration in glaucoma patients. Full article

In response to growing demand for autonomous and energy-efficient offshore operations, unmanned sailboats have emerged as promising platforms for next-generation marine applications. As the primary control surface, the rudder plays a pivotal role in enabling precise maneuvering and maintaining course stability. This study proposes an asymmetric aft-twisted flap rudder integrating a symmetric streamlined main rudder with an asymmetric flap. The design aims to enhance lift generation at small deflection angles, thus improving the hydrodynamic performance and response characteristics of rudder systems. The flap size for the conventional symmetric rudder was first determined from computational fluid dynamics (CFD) simulation results. To further improve lift performance, a 45° curved transition section was introduced at the junction between the main rudder and the flap to enhance flow attachment and reduce viscous drag. Building on this configuration, the asymmetric twisted flap was incorporated into the improved rudder design. CFD results indicate that the lift coefficient increased by approximately 27%. Comparative CFD analyses with the conventional symmetric flap rudder and the streamlined rudder revealed distinct coupled flow characteristics under various combinations of rudder and flap angles. These findings offer valuable insights into the hydrodynamic optimization of control surfaces in autonomous marine systems. Full article

To investigate the flow characteristics of movable water in coal under the influence of micro-nano pore fractures with multiple fractal structures, this study employed nuclear magnetic resonance (NMR) and multifractal theory to analyze gas–water seepage under different injection pressures. Then, the scale threshold for mobile water entering coal pores and fractures was determined by clarifying the relationship among “injection pressure-T₂ dynamic multiple fractal parameter seepage resistance-critical pore scale”. The results indicate that coal samples from Yiwu (YW) and Wuxiang (WX) enter the nanoscale pore size range at an injection pressure of 8 MPa, while the coal sample from Malan (ML) enters the nanoscale pore size range at an injection pressure of 9 MPa. During the water injection process, there is a significant linear relationship between the multiple fractal parameters log X(q, ε) and log(ε) of the sample. The generalized fractal dimension D(q) decreases monotonically with increasing q in an inverse S-shape. This decrease occurs in two distinct stages: D(q) decreases rapidly in the low probability interval q < 0; D(q) decreases slowly in the high probability interval q > 0. The multiple fractal singularity spectrum function f(α) has an asymmetric upward parabolic convex function relationship with α, which is divided into a rapidly increasing left branch curve and a slowly decreasing right branch curve with α₀ as the boundary. Supporting evidence indicates the feasibility of a methodology for identifying the variation in multiple fractal parameters of gas–water NMR seepage and the critical scale transition conditions. This investigation establishes a methodological foundation for analyzing gas–water transport pathways within porous media materials. Full article

Anaerobic digestion (AD) plays a crucial role in renewable energy production and waste management by converting organic waste into biogas and reduces greenhouse gas emissions. Optimized bioreactor performance depends on two main categories of factors: (1) reactor and geometric factors of agitator geometry, blade configuration, rotational speed, torque, power consumption, and the impeller-to-tank ration (d/D), and (2) fluid property factors of viscosity and flow characteristics, which relates turbulence, circulation patters, and stratification. Impeller power strongly influences nutrient distribution, gas exchange, and temperature uniformity within the reactor. While higher power inputs improve turbulence and prevent stratification, they also increase energy demand. This study evaluated fifteen blade configurations to determine the optimal fluid circulation using ANSYS 2024 R1 Fluent simulations. The bioreactor tank, with a diameter of 0.130 m and a height of 0.225 m, was tested at speeds ranging from 40 to 150 RPM. Among the single-blade configurations, the curved blade achieved the highest velocity at 0.521 m/s, generating localized circulations. The Rushton blade produced strong radial flows with a velocity of 0.364 m/s, while the propeller blade reached 0.254 m/s, supporting axial flow. In double-blade arrangements, the curved-propeller combination exhibited velocities between 0.261 and 0.342 m/s, enhancing fluid motion. The three-blade configurations resulted in the highest power consumption, ranging from 1.94 W to 1.99 W, with power increasing at higher RPMs and larger impeller sizes. However, torque values decreased over time. The most efficient mixing was achieved at moderate RPMs (80–120) and an impeller-to-tank diameter ratio (d/D) of approximately 0.75. These findings highlight the significance of blade selection in balancing mixing efficiency and energy consumption for scalable AD systems. Full article

Conventional throttling valves have non-linear flow characteristics. However, in precise processes of flow control requiring them, appropriate flow modulations are necessary to enable a linear flow response even under partial valve actuations. This paper formulates a hydraulic conical valve configuration that exhibits linear flow. Flow studies were conducted on a 24 mm orifice-sized Conventional Conical Valve (CCV) using Computational Fluid Dynamics (CFD) analysis with commercial code ANSYS Fluent 2022 R1 and through experiments. The mass flow curve for the CCV had a convex upward shape, implying that at all valve openings, its discharges lay above the linear discharge line. To create greater resistance to flow, a venturi was incorporated into the valve casing close to the downstream side of the valve seat, leading to a Venturi Conical Valve (VCV). CFD analysis revealed that the addition of the venturi added more flow resistance, while the identified optimal VCV was still unable to make the flow linear. Subsequently, labyrinth cavities were machined on the conical valve body of the VCV, changing it into a Labyrinth Venturi Conical Valve (LVCV). Experiments revealed that the discharge curve for the identified LVCV was nearly linear. The maximum linearity deviation of 45.76% found in the CCV decreased to 9.95% in the LVCV. The reduction in linearity deviation indicates an improved closeness of the valve discharge to the linear conditions. Full article

Concussion, or mild traumatic brain injury, is a significant public health challenge, with females experiencing high rates and prolonged symptoms. Reliable and objective tools for early diagnosis are critically needed, particularly in pediatric populations, where subjective symptom reporting can be inconsistent and neurodevelopmental factors may influence presentation. Five minutes of resting-state (RS) EEG data were collected from non-concussed and concussed females between 15 and 24 years of age. We first applied a deep learning approach to classify concussion directly from raw, RS electroencephalography (EEG) data. A long short-term memory (LSTM) recurrent neural network trained on the raw data achieved 84.2% accuracy and an ensemble median area under the receiver operating characteristic curve (AUC) of 0.904. To complement these results, we examined causal connectivity at the source level using information flow rate to explore potential network-level changes associated with concussion. Effective connectivity in the non-concussed cohort was characterized by a symmetric pattern along the central–parietal midline; in contrast, the concussed group showed a more posterior and left-lateralized pattern. These spatial distribution changes were accompanied by significantly higher connection magnitudes in the concussed group (p < 0.001). While these connectivity changes may not directly drive classification, they provide evidence of large-scale brain reorganization following concussion. Together, our results suggest that deep learning models can detect concussion with high accuracy, while connectivity analyses may offer complementary mechanistic insights. Future work with larger datasets is necessary to refine the model specificity, explore subgroup differences related to hormone cycle changes and symptoms, and incorporate data across different sports. Full article

Background: Expert guidelines recommend using pulse oximetry (PO) in the delivery room to monitor oxygen saturation (SpO₂) and heart rate (HR). Umbilical cord pulse oximetry (UCP) is a novel concept that, despite being postductal, could provide accurate measurements of SpO₂ and HR, as it overcomes barriers associated with skin pigmentation. Methods: This pilot study used NONIN pulse oximetry on an intact umbilical cord that underwent deferred cord clamping (DCC) to evaluate umbilical cord SpO₂ in a preterm asphyxiated ovine model (N of 5) with an HR of <100 bpm. The UCP HR served as a surrogate marker for umbilical vessel flow. A receiver operator characteristic (ROC) curve was used to evaluate UCP parameters with arterial saturations (SaO₂) and carotid HR between 2 and 10 min. Results: Following asphyxia, five preterm lambs underwent DCC for 4 min. A significant relationship was noted between SaO₂ and umbilical SpO₂ (area under the curve (AUC) of 0.907, CI 0.857–0.968, p < 0.0001) along with carotid and umbilical HR (AUC) of 0.842 (CI 0.663–0.902, p < 0.0001). Conclusions: In a translational preterm model, UCP accurately predicted preductal SaO₂ and carotid HR (a surrogate for umbilical flow). Using UCP in the delivery room will help guide supplemental oxygen and determine the optimal duration of clamping the umbilical cord. These proof-of-concept studies/pilot findings require validation with larger animal cohorts and newborn infants. Full article

Background: Cardiac surgery-associated acute kidney injury (CSA-AKI) is common and various tools are proposed to identify patients at risk of AKI. The determination of the Doppler-derived renal resistance index (RRI) is useful for detecting the occurrence of tubular necrosis or allograft rejection. This study questions the value of RRI in identifying CSA-AKI, defined according to the renal risk, injury, failure, loss of kidney function, and end-stage kidney disease (RIFLE) classification. Methods: We conducted a prospective, unblinded, observational study in patients undergoing open heart surgery. Clinical and surgical data were collected from the electronic medical files and the Cleveland score was calculated for each patient. Before the surgery and upon admission to the intensive care unit (ICU), blood flow in the renal cortical or arcuate arteries was measured and the RRI was computed. The capability of preoperative serum creatinine, the Cleveland score, and the preoperative and postoperative change in RRI were investigated with the area under the receiver operating characteristic curve (ROC-AUC) to predict the AKI. Results: Within the first five postoperative days, 31.4% developed CSA-AKI. All patients with stage 1 AKI recovered normal creatinine levels before ICU discharge while those with stage 2 or 3 (AKI 2/3) exhibited persistent changes. To discriminate AKI 2/3, the ROC-AUC was less than 0.7 for the preoperative serum creatinine and RRI, 0.879 for the Cleveland score, and 0.710 for the postoperative RRI. The change between the preoperative and postoperative RRI (dRRI) provided a ROC-AUC of 0.825 (sensitivity 72.7% and specificity 96.6%) with an optimal cut-off point at 9.4%. Conclusions: Noninvasive determination of RRI is helpful for detecting PO-AKI and provides additional information to clinical markers. Full article

This paper is based on the fish lateral line sensing mechanism and aims to determine the coupling relationship between the flow field sensing signal and target source position information. Firstly, according to the flow field distribution characteristics of the target source, the equivalent multipole model of the flow field disturbance during the underwater motion of the SUBOFF model is constructed, and then the target localization function based on the least squares method is established according to the theory of potential flow, and the residual function of the target localization is solved optimally using the quasi-Newton method (QN) to obtain the estimated position of the target source. On this basis, a curved bionic lateral line sensing array is constructed on the surface of a robotic fish, and the estimated location of the target source is obtained. The curvilinear bionic lateral line sensing array is constructed on the surface of the robotic fish, and the effectiveness and robustness of the above localization methods are analysed to validate whether the fish lateral line uses the pressure change to sense the underwater target. Full article