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This paper presents comparable sets of the no-load power loss as a product of windage and churning behaviors of a family of various rotating parts (i.e., disc, spur gear, straight bevel gear, and orthogonal face gear). Experimental measurements were carried out under pure air only and under partial immersion in oil to qualify and quantify the windage and churning effects of no-load power losses of a family of spur, bevel, and face gears along with a representative disc as the baseline. Aiming at exploring the influence of gear teeth on the total no-load power losses, two different theoretical analytical approaches are introduced to account for the churning contributions, by which the total power losses are estimated. Both analytical approaches compare well with the experimental findings. Furthermore, a spatial intersecting cross-axis gear (e.g., straight bevel gear and orthogonal face gear) results in higher no-load power losses than that of a representative disc or a parallel-axes gear. The significance of gear teeth (gear vs. disc) on windage behavior is presented, as well as the gear windage effects on the churning phenomenon in a high-speed splash-lubricated gear.

To suppress the adverse effect of the gear windage phenomenon in the high-speed aeronautic industry, a shroud as an effective alternative strategy is usually to enclose gears to reduce the windage behaviors of high-speed gears. To deeply understand these no-load power losses, this paper proposes a new simulation methodology based on the Lattice Boltzmann method to study the windage losses of a shrouded spur gear and conducts a series of numerical studies. The models reproduce a shroud spur gear varying radial and axial clearances to evaluate the influence of casing walls on windage losses. The simulation results were then compared with experimental values, showing a satisfactory agreement. Furthermore, a torque containment factor integrating the air compressibility at high Mach numbers is introduced to represent the reduction in torque (windage power losses) for the shrouded gear compared to the free case, and the theoretical formulae for predicting windage power losses are further improved for better applicability as the tight shroud approaches the gear during the preliminary design stage.

Due to the limited spatial constraints and complex motion of aerospace planetary gear reducers, under-race lubrication is employed for planetary gear bearings to ensure adequate lubrication performance with minimal oil flow. In this study, a specialized experimental setup was designed and developed to quantitatively evaluate the oil discharge at the bearing end face under under-race lubrication conditions. The results were compared with CFD simulations conducted under identical operating conditions, revealing discrepancies within an acceptable range. Subsequently, an in-depth investigation was conducted to examine the influence of various input parameters on the oil volume fraction and the churning loss. A surrogate model based on the Kriging method was constructed, and the NSGA-II algorithm was employed for multi-objective optimization of the lubrication design, leading to the identification of optimal input parameters.

After COVID-19 pandemic, there has been an upward trend in ( ) infections across Asia. The COVID-19-induced immunological impairment may increase the risk of adverse outcomes in -infected patients, yet studies in this area remain limited. We investigated the association between infection and adverse pregnancy outcomes in the post-COVID-19 era. We conducted a single-center cohort study in Guangzhou, China, from February 2023 to June 2024, involving pregnant women. A total of 186 participants were included, with 49 in the group (tested positive for immunoglobulin M antibody (MP IgM)) and 137 in the control group. Propensity score weighting analysis was performed to control bias and estimate the effect size. The incidence of adverse pregnancy outcomes in the group was not significantly different from that in the control group. The odds ratio (OR) for adverse maternal events after propensity score weighting (PSW) was 1.25 (95% confidence interval [CI], 0.62 to 2.55;  = 0.530), and the PSW OR for adverse neonatal events was 0.95 (95% CI, 0.49 to 1.84;  = 0.884). However, in the subgroups of advanced maternal age (AMA, age ≥ 35, n=29) and primiparous women (n=80), the incidence of adverse pregnancy outcomes was significantly higher in the group. Additionally, the clinical manifestations of infection in the post-COVID-19 era were consistent with those observed prior to the pandemic. In the post-COVID-19 era, evidence remains insufficient to conclude that infection increases the risk of adverse pregnancy outcomes in the general pregnant population. Exploratory subgroup analyses suggest possible signals of risk within subgroups of AMA and primiparous women.

Combating climate change by increasing urban carbon storage is one of the critical issues which urban policymakers must address. Understanding the characteristics and driving factors of carbon storage changes during urbanization can assist urban managers in formulating responsive land use policies. This study employs the INVEST model to evaluate carbon storage in Shanghai from 2000 to 2020, analyzing land use changes and their carbon impacts. It analyzes the transformation of land use in Shanghai during the same period and its impact on carbon storage. Using a 1 km grid for sampling, this study examines the spatiotemporal distribution patterns of carbon storage in Shanghai. Furthermore, it employs linear regression to discuss the social and economic drivers influencing carbon storage in the city. Carbon storage in Shanghai, predominantly from cultivated land and artificial surfaces, increased from 16.78 Mt in 2000 to 18.40 Mt in 2020, with an annual rise of 0.81 Mt. The spatial distribution of carbon storage exhibited a stable southeast-northwest pattern, with variations in dispersion between the north-south and east-west directions. The distribution of carbon storage shifted from a bimodal to a unimodal pattern, indicating an overall increase. There was a significant positive correlation between carbon storage and both the per capita green space area and the industrial output value, which can be attributed to Shanghai’s policies on green industrial development. This research aids in formulating land use policies to enhance urban carbon storage.

This paper investigates the special phenomenon that the practical immersed depth of a spiral bevel gear as the driving gear under splash lubrication is significantly less than the static depth. To quantify the practical immersion depth, a computational fluid dynamics (CFD) approach integrated with image processing techniques is utilized to determine the dynamic immersion depth and the associated churning power loss. First, a theoretical method is developed to estimate the churning losses of the bevel gear by replacing the static immersion depth with the practical dynamic immersion depth. Subsequently, the CFD method, which incorporates the overset mesh technique and the volume-of-fluid (VOF) method, is employed to simulate the gear churning phenomenon. Meanwhile, the dynamic immersion depth is determined through image processing techniques that analyze the oil distribution characteristics in the splash-lubricated bevel gear. Finally, experimental results obtained from a dedicated lubrication test rig are favorably compared with the numerical results, confirming that the practical dynamic immersion depth is an accurate and effective parameter for calculating power losses.

Under the context of rapid urbanization and climate change, urban ecosystem services (ES) have undergone dramatic transformations. Elucidating the trade-off and synergy relationships among ES and quantifying how urbanization mediates these relationships are critical to achieving urban sustainability. Focusing on Shanghai during 2000–2020, we quantified three climate-related ES—water yield (WY), urban cooling (Heat Mitigation Index, HMI) and carbon storage (CS)—with the InVEST model. We then examined the spatio-temporal evolution of these services, analyzed their trade-offs and synergies, and examined the underlying urbanization drivers. Results show that total WY increased by 76%, with peak volumes concentrated in the central districts; HMI declined, with low-value zones spreading inward; CS rose and became spatially more homogeneous. WY–HMI trade-offs intensified, whereas CS–HMI were synergistic (r = 0.33–0.61) except in core districts where built-up expansion created trade-offs. CS–WY trade-offs weakened, becoming synergistic in most districts by 2020. HMI loss was driven by GDP and industrial output (p < 0.05). Per-capita green-space area was positively correlated with HMI but exerted no significant influence on CS or WY, highlighting the limitations of ecological interventions focused on single ES enhancement.

Urban flooding, intensified by climate change, poses significant threats to sustainable development, necessitating accurate precipitation projections for effective risk management. This study utilized Bayesian Model Averaging (BMA) to optimize CMIP6 multi-model ensemble precipitation projections for Shanghai, integrating Delta statistical downscaling with observational data to enhance spatial accuracy and reduce uncertainty. After downscaling, RMSE values of daily precipitation for individual models range from 10.158 to 12.512, with correlation coefficients between −0.009 and 0.0047. The BMA exhibits an RMSE of 8.105 and a correlation coefficient of 0.056, demonstrating better accuracy compared to individual models. The BMA-weighted projections, coupled with Soil Conservation Service Curve Number (SCS-CN) hydrological model and drainage capacity constraints, reveal spatiotemporal flood risk patterns under Shared Socioeconomic Pathway (SSP) 245 and SSP585 scenarios. Key findings indicate that while SSP245 shows stable extreme precipitation intensity, SSP585 drives substantial increases—particularly for 50-year and 100-year return periods, with late 21st century maximums rising by 24.9% and 32.6%, respectively, compared to mid-century. Spatially, flood risk concentrates in peripheral districts due to higher precipitation exposure and average drainage capacity, contrasting with the lower-risk central urban core. This study establishes a watershed-based risk assessment framework linking climate projections directly to urban drainage planning, proposing differentiated strategies: green infrastructure for runoff reduction in high-risk areas, drainage system integration for vulnerable suburbs, and ecological restoration for coastal zones. This integrated methodology provides a replicable approach for climate-resilient urban flood management, demonstrating that effective adaptation requires scenario-specific spatial targeting.

The deep-sea is rich in mineral resources, and deep-sea polymetallic nodules are considered to be the most likely resource for commercial exploitation. Since the discovery of polymetallic nodules by mankind, researchers around the world have made long and arduous explorations in the exploitation of deep-sea polymetallic nodules and have proposed various mining methods, such as the dragging bucket type, the continuous bucket rope type, the automatic shuttle boat type, and the pipeline -lifting type, and have carried out technical verification accordingly. In the collection of seabed polymetallic nodules, the development and testing of towed type, spiral-driven type, crawler self-propelled type, and suspended type technologies have been carried out, basically realizing the mining technology verification of seabed polymetallic nodules and providing technical support for commercial development. However, according to the demand for commercial development, there are still many technical difficulties in polymetallic nodule-collecting technology, and more focus needs to be placed on the efficiency, environmental protection, intelligence, safety, and reliability of the collecting system in the future. This paper compares the existing progress in collection technology and equipment, and provides ideas and references for the research and development of deep-sea polymetallic nodule-mining technology and equipment.

•Evaluating the safety of inactivated COVID-19 vaccines during the peri-pregnancy period for pregnant women and neonates.•No significant difference in the incidence of premature rupture of membranes or neonatal adverse events between groups.•IPTW method is employed prior to regression analysis, which can mitigate the bias in the observational study.•Robust evidences provide reference for the use of inactivated COVID-19 vaccines for pregnant women in clinical practice. Pregnant women have been excluded from vaccination of COVID-19 due to the lack of strong clinical evidence, which may place pregnant women at greater risk of contracting COVID-19. We conducted this study in China to investigate the maternal and neonatal safety of inactivated COVID-19 vaccination administered during the peri-pregnancy period. This prospective observational cohort study enrolled pregnant women who received pregnancy care between January 1, 2021, and December 31, 2021. Pregnant women were categorized into vaccine group (n = 60) and control group (n = 60) based on whether they had received an inactivated COVID-19 vaccine within peri-pregnancy period. The primary outcomes were the incidence of maternal premature rupture of membranes (PROM) and neonatal adverse events, including induced labor/death, premature birth, low birth weight, and neonatal intensive care unit (NICU) admission and several secondary outcomes related to pregnant women and neonates. Inverse probability treatment weighting (IPTW) was employed to adjust for baseline covariates. Linear and logistic regression models were established after IPTW for continuous and binary outcomes, respectively. In sensitivity analysis, E-values were calculated and propensity score matching analysis and multivariate regression analysis used to demonstrate the robustness of IPTW results. Moreover, vaccination time subgroup analysis and medication subgroup analysis were conducted. Out of 120 neonates delivered, there was no significant difference in PROM (25.42 % vs. 19.67 %, p = 0.438) or neonatal adverse events (11.86 % vs. 4.92 %, p = 0.148) between the vaccine and control groups. Moreover, among the secondary outcomes only serum alanine transaminase (ALT) at first trimester had a statistically significant difference between the groups, ALT levels were significantly higher in the vaccine group during the first trimester (20.67 ± 20.34 vs. 13.05 ± 9.43; RR: 5.38; p = 0.04). In sensitivity analysis, the E-values calculated for the primary outcomes PROM and neonatal adverse events are 2.04 and 5.00 respectively. PSM analysis and multivariate regression analysis reached the same conclusion. The results of primary outcomes are both consistent across the vaccination time subgroup and medication subgroup. The sensitivity analysis illustrates the robustness of our results, so we can conclude that the vaccination of inactivated COVID-19 vaccine during the peri-pregnancy period is safe for both the pregnant woman and neonates no matter what time of vaccination and the use of medication. In addition, it is recommended to monitor ALT levels throughout the first trimester of pregnancy.