Search Results (7,597)

Tip seal leakage in shrouded steam turbines can significantly affect the aerodynamic performance of downstream blade rows. An unsteady three-dimensional numerical model of a 1.5-stage high-pressure steam turbine is established using ANSYS CFX (ANSYS2021) with the SST k–ω turbulence model. Tip seal clearances of 1.0, 1.5, and 1.9 mm are investigated using the Q-criterion and vorticity transport equation to characterize leakage-vortex evolution and its interaction with the mainstream. The results show that increasing tip seal clearance strengthens leakage flow and expands its interaction region. The expansion term exhibits a relatively stronger influence on vorticity variation near the seal teeth, whereas the vortex stretching term plays a significant role in leakage-vortex evolution near the seal inlet, outlet, and cavity. Leakage vortices interact with the rotor wake, intensifying velocity gradients and aerodynamic loss, with pronounced flow distortion near 85% rotor span. The disturbance is further transported to the downstream stator, causing marked variations in flow angle, circumferential velocity, and static pressure in the upper-span region. At 95% and 99% blade heights, pronounced differences in suction-surface static pressure occur within the forward 80% of the chord length. These findings clarify the aerodynamic consequences of tip seal leakage and its downstream effects. Full article

Potato stolon research has emphasized stolon-tip tuberization, leaving the transition of basal axillary buds into subterranean stolons poorly characterized. Using cv. Désirée, we characterized this transition at IS0 immediately before soil covering and at 5, 7, 9, and 11 d thereafter (IS5, IS7, IS9, and IS11) by morphological, histological, and transcriptomic analyses. At IS5, external morphology changed little, although internal tissue reorganization was evident. During IS7–IS9, buds progressively reoriented, enlarged basally, and established a subterranean lateral axis. By IS11, white stolons had formed and entered post-initiation elongation without visible stolon-tip swelling. PCA separated IS0 and IS11 from the intermediate stages, and adjacent-stage differential expression identified the largest DEG sets in IS0–IS5 and IS9–IS11. Direction-resolved GO and KEGG enrichment distinguished successive transitions: early oxidative/defense and phenylpropanoid-related categories; intermediate changes in transport, photosynthesis, redox metabolism, and cytoskeletal organization; and later enrichment of translation-, proteasome-, and cell-division-related categories. Mfuzz clustering provided a complementary overview of broad temporal trajectories, including IS5-associated C6, distinct C3 and C5 patterns during initiation, and IS11-associated C2. RT-qPCR profiles of StBRC1b, StWUS, StWOX5, StCCD8, StSP6A, and StSP3D were broadly consistent with the RNA-Seq trends. These results establish a time-resolved framework for soil-covering-induced stolon initiation and subsequent elongation. Full article

Rejuvenation of the perioral region using minimally invasive aesthetic techniques is frequently used to address age-related changes. While hyaluronic acid-based dermal fillers are a frequently used treatment, limited data are available on the injectable biostimulator poly-L-lactic acid (PLLA-SCA; Sculptra^®). This study described the aesthetic outcomes of PLLA-SCA injectable treatment for perioral rejuvenation using a series of patient cases collected up to 8–13 months post-first injection. This retrospective, single-center case series involved adults (age ≥ 18 years) who presented with concerns related to age-associated changes in the perioral region and were treated with PLLA-SCA as part of a full-face rejuvenation regimen. Reconstituted PLLA-SCA was injected subdermally, as superficially as technically feasible, using a 25-gauge blunt-tip cannula equally across both sides of the full face, adjusted to individual findings, at Baseline (Day 0) and at Weeks 8 and 16, with a follow-up at Week 28. This series of patient cases demonstrated positive aesthetic outcomes with PLLA-SCA that included visible softening of the vertical lip lines at rest and restoration of a more horizontal commissural axis, preserved dynamic expression, improved definition of the Cupid’s bow and the vermilion border, reduced prominence of the mentolabial crease, improved midfacial support, and improvement of peri-commissural skin texture. For all cases, the investigator-rated Global Aesthetic Improvement Scale score at Week 28 was either “very much improved” or “much improved”, and the patient-reported satisfaction was rated at 5/5. Adverse events were limited to mild, transient injection-site bruising that quickly resolved without intervention, and short-lived edema; no nodules, vascular events, or delayed-onset reactions were observed. While these preliminary clinical observations at Week 28 suggest that PLLA-SCA can be used in a safe and effective manner for rejuvenation of the perioral region, future, larger, and longer-duration studies are warranted. Full article

Reliable electricity supply in Colombia’s Non-Interconnected Zones requires sustainable and low-cost energy technologies. Vertical-axis hydrokinetic turbines are promising for this purpose; however, their relatively low power coefficient remains a major challenge. This study combines transient 2D and 3D $k$–$\omega$ SST computational fluid dynamics (CFD) simulations with hydraulic channel experiments to investigate a hybrid Darrieus–Savonius turbine. A 27-case Design of Experiments (DoE) based on 2D CFD was first applied to screen the effects of rotor radius ratio (RR), attachment angle (AA), and water velocity. Within the investigated design space, the configuration with $\mathrm{R}\mathrm{R}=0.5$ and $\mathrm{A}\mathrm{A}=0^{\circ }$ produced the most favorable average performance. The selected configuration was subsequently analyzed using 3D CFD and experimentally evaluated at TSR values of 1.0, 1.1, and 1.2. At TSR = 1.0, the 3D model predicted ${\mathrm{C}}_{\mathrm{P}}=0.1525$, closely matching the experimental value of 0.1541 with a relative error of 1.05%. The results demonstrate that 2D CFD is useful for computationally efficient parameter screening and qualitative trend identification, but it overpredicts absolute performance because it neglects blade tip vortices, spanwise flow, and volumetric wake interactions. Three-dimensional CFD is therefore required for reliable performance prediction and analysis of the complex flow structures governing hybrid hydrokinetic turbine behavior. Full article

Megastigmus sabinae Xu et He (Hymenoptera: Torymidae) is an oligophagous seed pest overwintering within Juniperus przewalskii cones in the alpine Qilian Mountains. Understanding its cold adaptation is critical for forest pest management. To investigate its overwintering mechanisms, we monitored field temperatures and larval development. Subsequently, larvae were subjected to a series of low-temperature treatments under laboratory conditions. We then assessed survival rates, supercooling points (SCPs), free water content, and the transcriptomic profiles of water-regulatory genes. Field data revealed that larvae enter a quiescent state when ambient temperatures drop below 5 °C. Laboratory acclimation at 0 °C significantly improved larval survival at −10 °C and markedly depressed the SCP by approximately 6 °C. Notably, free water content remained completely stable across all temperature treatments. Consistent with this dehydration-independent phenotype, transcriptomic analysis showed that the majority of 17 aquaporins (AQPs) and a Capa receptor gene lacked differential expression. However, two specific AQP genes (TIP1-1 and AQPN) were significantly upregulated. Collectively, M. sabinae larvae employ a freeze-avoidance strategy driven by dehydration-independent SCP depression and highly targeted transcriptional adjustments of specific water channels. Full article

Akerlof’s classical theory of the “Market for Lemons,” which conceptualizes adverse selection driven by information asymmetry, established the foundation of information economics. While the traditional model assumes static equilibria among a limited number of agents, analyzing its behavioral dynamics within large-scale, complex network environments remains a highly relevant task in computational social science. This study extends the classical lemon market model into a nonlinear dynamical system on adaptive networks. We mathematically elucidate macro-level social phase transitions—specifically structural exclusion such as scapegoating and collective ostracism—induced by computational cognitive limits, and evaluate optimal intervention strategies to mitigate these systemic failures. Multi-agent simulations utilizing large-scale tensor operations demonstrate that autonomous edge rewiring under incomplete information does not merely result in the uniform displacement of high-quality goods as predicted by static theory. Instead, the network self-organizes into an irreversible structural division: a core group of influential agents monopolizes high-quality information, while marginalized agents are isolated into a peripheral “lemon echo chamber” where only low-quality information circulates. To address this structural pathology under a resource constraint limiting intervention to 10% of the total agents, we evaluated two distinct approaches. The results indicate that providing informational support to influential hubs functions as a trap that exacerbates systemic inequality, superficially elevating the overall market evaluation but permanently fixing the exclusion gap. Conversely, the forced maintenance and protection of “weak ties” bridging disconnected clusters constitutes the mathematically optimal solution to dissolve fragmentation, effectively eliminating the price gap and facilitating social inclusion. Furthermore, this study demonstrates that the mechanism of social exclusion exhibits strong hysteresis effects. A distinct tipping point governs the progression toward a fragmented lemon echo chamber. Interventions implemented after crossing this critical threshold fail to restore the system to its baseline state despite identical resource expenditure, confirming the presence of an irreversible phase transition. These findings establish that the collapse dynamics outlined in the classical lemon market serve as a generalized model for explaining contemporary collective ostracism driven by information cascades. Consequently, the analysis highlights the necessity of early intervention prior to critical thresholds and the systemic preservation of structural bypasses rather than post-hoc remediation. Full article

Frictional energy piles are a more desirable form of shallow geothermal energy utilization. A pure friction pile condition cannot be achieved in field tests. In this study, foam was placed beneath the model pile tip to weaken the end-bearing resistance. The effects of different cyclic temperature patterns (including cyclic path, external load, and variable temperature duration) on the bearing characteristics of pure friction energy piles are investigated by conducting model tests in a self-designed model box, and the variation patterns of pile stress–strain and pile-top displacement are measured. The results show the following: (1) Under no load, the displacement of the pile top changes with temperature; each round of temperature change produces a partial irrecoverable displacement, and the pile maintains a raised state at the end of both rounds with no stress accumulation. (2) Under the combined action of working load and cyclic temperature, the pile strain reaches its peak and then partially rebounds. Thermal stress accumulates progressively with increasing cycle numbers, and after the cycling ends, an irrecoverable settlement displacement (0.52% D) remains at the pile top and continues to increase. (3) The temperature cycle caused the soil volume to shrink and decreased the shear strength of the pile–soil interface, resulting in a decrease in the ultimate bearing capacity of the test pile compared to the initial state. Full article

High carbonate alkalinity (CA) is a major constraint on shrimp culture in saline–alkaline waters. The hepatopancreas is central to shrimp immunity and metabolic regulation. Litopenaeus vannamei underwent a 7-day exposure period to 5 mmol/L CA, followed by a subsequent 7-day recovery phase after removal of the stressor. The physiological regulatory mechanism of the hepatopancreas during CA stress and recovery was investigated by integrating multiple biological levels including histomorphology, antioxidant and immune indices, energy metabolism, and metabolite profiles. Results showed that CA stress induced structural changes in the hepatopancreas and triggered stress responses. Specifically, a significant upregulation was observed in genes involved in antioxidation (romo1, nrf2, gpx, hsp70), apoptosis (casp-9, casp-3), endoplasmic reticulum (ER) stress (ire1, xbp1), immune defense (alf, crus, pen-3, lys, propo), and detoxification (cyp450). CA stress also increased osmoregulatory genes (ccp, nhe, ca, aqp, vatp, nka-β, nka-α), whereas clc and tip4 were suppressed. CA stress reduced the levels of energy-metabolism-related biochemical indicators, including glucose (GLU), pyruvic acid (PYR), lactic acid (LAC) and triglycerides (TG), while markedly inducing the expression of genes involved in carbohydrate metabolism (ldh, pdh, hk, pk), lipid metabolism (ampk, srebp, fas), the tricarboxylic acid (TCA) cycle (mdh, cs, idh, odh, sdh, fh), and the electron transport chain (ETC) (ndh, cytc, coi, cco, atph). Moreover, the hepatopancreatic metabolic profile was remodeled, especially “phenylalanine, tyrosine and tryptophan biosynthesis” and the metabolism of β-alanine, arachidonic acid, linoleic acid, and sphingolipids being substantially altered during both the stress and recovery phases. Several functional metabolites linked to stress responses were further pinpointed. Following stress relief, some physiological parameters partially recovered, yet overall function failed to return to normal. Collectively, CA stress compromised hepatopancreatic homeostasis by damaging morphological integrity, eliciting stress and immune responses, and perturbing energy metabolism and metabolite homeostasis; these adverse effects were not readily reversible in the short term. Full article

Purpose: Excessive drill advancement after cortical breakthrough is a potential safety concern in orthopaedic procedures. We developed a data-driven approach to estimate the drill-tip position relative to the far cortex prior to breakthrough using time-series thrust force and spindle torque signals. Methods: Drilling experiments were performed on 268 porcine cortical bone specimens at a constant feed rate of 0.5 mm/s. A long short-term memory network was trained to estimate the drill-tip position from filtered force and torque signals. The reference position was derived from breakthrough timing confirmed by high-speed imaging and the programmed feed rate. Performance was evaluated using mean absolute error within the −2 to +2 mm peri-breakthrough interval. Two post hoc analyses examined whether model performance exceeded an elapsed-time baseline and whether pre-breakthrough force patterns were more consistent when expressed relative to breakthrough position than to drilling onset time. Results: The combined-input LSTM achieved an MAE of 0.20 mm, compared with 0.23 mm for force alone and 0.24 mm for torque alone. Among the representative architectures evaluated, LSTM showed the lowest regression error. A signal-blind time-only baseline yielded an MAE of 0.54 mm. The association between cortical thickness and force-decline onset was weaker when expressed in spatial coordinates relative to breakthrough than when expressed as time from drilling onset (R² = 23% vs. 74%). These findings suggest that force and torque signals contained information associated with proximity to breakthrough beyond that provided by average drilling duration alone. Conclusion: Converting sensor-derived resistance patterns into spatially anchored positional information may support proactive strategies such as controlled deceleration before penetration. The proposed approach represents a step toward exemplifying the emerging concept of surgeon-assisting Physical AI. Full article

This paper proposes an annular suction caisson specifically designed to reinforce in-service monopiles and upgrade existing offshore wind farms to accommodate larger-capacity wind turbines. During penetration of the annular suction caisson into clay, the existing monopile restricts the inward migration of soil into the internal space of the caisson, promoting upward soil displacement and consequently increasing the height of the soil plug formed inside the caisson. In addition, the strain-softening behavior causes varying degrees of strength degradation in the clay along the caisson wall. The softened zones extend approximately one caisson wall thickness on the inner side and 1.2 times the wall thickness on the outer side of the caisson. Both effects should be considered for accurately predicting the penetration resistance of annular suction caissons. Therefore, three-dimensional large-deformation finite element analyses were performed to investigate the penetration behavior of annular suction caissons in strain-softening clay. A comprehensive parametric study was conducted to quantify the soil plug heave and overall penetration resistance. Meanwhile, the soil flow mechanism at the caisson tip, the evolution of clay strength along the caisson wall, and the formation characteristics of the internal soil plug were systematically examined. Based on the numerical results, a theoretical approach was developed to evaluate the penetration resistance of annular suction caissons. Full article

Under China’s dual-carbon targets, mountainous areas are critical ecological barriers with substantial carbon-sink potential. This study investigated the effects of land-use and land-cover change (LUCC) on carbon emission (CE), carbon storage (CS), and carbon balance in Longhui, Dongkou, and Suining counties in the central Xuefeng Mountains. Using LUCC data from 2000 to 2020, we combined the InVEST, PLUS, and Gray Models with an emission-coefficient method to reconstruct historical LUCC and analyze the spatiotemporal patterns of CE and CS. Future carbon balance was then modeled for 2040 under natural development (ND), ecological protection (EP), and economic development (ED) scenarios. The results indicated that: (1) from 2000 to 2020, construction land doubled, whereas cultivated land and forest land decreased significantly; (2) net CE increased by 3.5-fold, with construction land acting as the dominant carbon source and forest land serving as the primary carbon sink. CS declined by 3.7 × 10⁵ t and exhibited a spatial pattern of high in the west, low in the east. The carbon supply-demand ratio (CSDR) showed a continuous downward trend, with central towns approaching carbon deficits. (3) Projections for 2040 indicated that Taohong Town will face a carbon deficit under the ED, while nearing the critical threshold under the ND. Although the EP prevents a deficit, the town remains vulnerable near the tipping point; in contrast, western ecological townships maintain substantial carbon surpluses. Accordingly, four carbon-balance regulation zones are identified, and differentiated governance strategies are proposed. These findings provide a scientific basis for carbon-balance regulation and low-carbon territorial planning in mountainous counties. Full article

Archimedes Spiral Wind Turbines (ASWTs) are suitable for small-scale urban wind applications, but changing the blade angle can also change the rotor dimensions under different geometric constraints. This study examines these coupled effects by comparing five ASWT configurations with blade angles of 30°, 45°, and 60° under fixed-diameter (Fixed D) and fixed-axial-length (Fixed L) conditions. Steady three-dimensional Reynolds-averaged Navier–Stokes simulations using the Multiple Reference Frame method were conducted to evaluate the power coefficient ($C_p$), torque coefficient ($C_t$), and mid-plane pressure and velocity fields. The numerical setup was assessed through grid-independence and reference-data comparisons. Under the Fixed D constraint, the 60° configuration achieved the highest $C_p$ of 0.2915 at a tip-speed ratio (λ) of 1.9, whereas the 30° configuration reached a maximum $C_p$ of 0.1792 at λ = 1.0. Under the fixed L constraint, the corresponding $C_p$ values were 0.2869 at λ = 2.5 for the 60° configuration and 0.1713 at λ = 0.8 for the 30° configuration. The baseline 45° configuration achieved a maximum $C_p$ of 0.2444 at λ = 1.5. The torque coefficient decreased with increasing λ for all configurations, while the pressure and velocity fields differed between the two constraints at the same blade angle. These results indicate that blade angle should be evaluated together with rotor diameter, axial length, and the installation envelope, because a larger rotor or swept area does not necessarily produce a proportional increase in normalized aerodynamic efficiency. Full article

To harness the terrain adaptability of legged systems and the high-speed efficiency of wheeled platforms, this paper presents the design of a novel leg-wheel hybrid mobile platform intended for enhanced obstacle negotiation. The proposed system comprises six identical leg-wheel modules, each integrating a closed-chain mechanical leg with an independently driven wheel mounted at the tip. The platform operates in two distinct modalities: a pure leg mode and a leg-wheel composite mode. In the leg mode, locomotion is driven by crank motors, providing exceptional mobility across uneven terrain. Conversely, the composite mode utilizes both crank and pitch link motors to facilitate obstacle surmounting, while hub motors ensure high-efficiency propulsion. Comprehensive gait planning for both modes is conducted, accompanied by a detailed analysis of the platform’s obstacle-negotiation capabilities. Kinematic analysis and gait simulations validate the platform’s superior mobility and efficient obstacle-crossing performance under the dual-mode strategy. Prototype experiments further confirm the feasibility of the mechanical design, demonstrating significant proficiency in traversing obstacles. This research contributes a novel design exploration by serially combining a closed-chain leg mechanism with an actuated wheel. The adopted closed-chain architecture offers the distinct advantages of high foot clearance and a single degree of freedom (DoF), which are critical for achieving reliable and effective obstacle-surmounting capabilities. Full article

Background and Objectives: Presurgical infant orthopedics aims to reduce cleft severity and facilitate primary surgical repair during the early neonatal period, when increased tissue plasticity enhances molding. Nasoalveolar molding is widely used but requires intraoral appliances, laboratory support, specialized training, and frequent follow-up visits, which may limit accessibility and adherence. This case series reports the clinical application of presurgical lip–alveolus–nose approximation (PLANA), an extraoral technique for early presurgical cleft management, and describes the clinical changes observed during treatment in four infants. Materials and Methods: A prospective case series conducted in neonates with non-syndromic unilateral or bilateral cleft lip and/or palate referred within the first 10 days of life to the Alabama Cleft Center. Treatment consisted of a prefabricated silicone nasal aligner combined with hydrocolloid lip adhesive taping. No intraoral plates or dental impressions were used. Devices were worn 20 to 22 h daily. Follow up occurred every 2 to 4 weeks, with remote monitoring used when appropriate. Qualitative clinical observations focused on apparent changes in nasal symmetry, columellar length, septal alignment, nasal tip projection, premaxillary position, nostril dimensions, alar base width, cleft width, and lip approximation, as well as feeding tolerance, skin tolerance, and treatment adherence. These observations were assessed qualitatively through serial clinical examinations and clinical photographs; no standardized quantitative morphometric measurements were performed. Results: Four infants with complete unilateral or bilateral cleft lip and palate received PLANA treatment. Serial clinical examinations and photographs documented qualitative changes in nasolabial morphology over the course of treatment in all four patients. Qualitative clinical assessment of serial photographs and examinations suggested greater apparent nasal symmetry, apparent columellar elongation, more central-appearing nasal alignment, increased apparent nasal tip projection, apparent cleft-width reduction, and progressive lip approximation. In unilateral clefts, changes were observed in both the cleft and non-cleft nasal sides, while bilateral clefts demonstrated changes in nasal morphology bilaterally. No device-related complications or clinically significant skin intolerance were documented during the reported treatment periods. Parent-reported device wear was approximately 20–22 h per day. Conclusions: In this four-patient prospective descriptive case series, PLANA was applied clinically, with no clinically significant treatment-related complications documented during the reported treatment periods. Serial clinical observations suggested changes in nasolabial morphology during treatment. Given the small sample size, absence of a contemporaneous control group, and qualitative nature of the assessments, these findings should be interpreted as preliminary and hypothesis-generating rather than as evidence of treatment efficacy or comparative effectiveness. Larger prospective, multicenter comparative studies incorporating standardized quantitative measurements, objective adherence assessment, and long-term surgical and aesthetic outcomes are needed to evaluate the effectiveness, reproducibility, and clinical applicability of the PLANA approach. Full article