Search Results (183)

Multi-storey solar chimneys are often evaluated using shaft-outlet airflow, which may conceal uneven airflow distribution among floors. A shaft may provide adequate extraction while upper floors receive insufficient air or experience reverse airflow. This study examined the relationship between neutral plane (NP) position and floor-specific airflow to guide adjustments to openings in a nine-storey building with two solar chimneys. Three-dimensional unsteady computational fluid dynamics (CFD) simulations quantified airflow rate and direction on each floor, airflow at the shaft outlet, and NP height. During controlled case screening at a prescribed absorber-plate heat flux of 484.24 W/m², each shaft’s outlet airflow exceeded the combined requirements of its connected floors, although reverse airflow occurred at 2F and 7F–9F. Reducing selected lower-floor opening areas raised the NP from 11.5 to 12.4 m in the west-shaft zone and from 29.2 to 35.9 m in the east-shaft zone, redistributing airflow upward without changing shaft geometry. Across the six evaluated transition-season months, compliance rates were 100% on 1F–7F, 79.2% on 8F, and 0% on 9F. Airflow remained inward on 8F throughout, whereas reverse airflow persisted on 9F. This study demonstrates that joint assessment of NP position alongside shaft-outlet airflow and floor-specific requirements distinguished insufficient extraction from uneven distribution and informed opening adjustments. Within the evaluated building and design space, however, the tested opening-area strategy did not resolve reverse airflow on 9F and would need to be combined with additional measures targeting the upper-floor pressure and airflow path to achieve building-wide compliance. Full article

Background/Objectives: A restrictive spirometric pattern (RSP), characterized by reduced forced vital capacity (FVC) with a preserved FEV1/FVC ratio, has been associated with adverse health outcomes and metabolic disorders. This study investigated differences in the prevalence of RSP and pulmonary function between 2019 and 2024 among Korean adults. Methods: This cross-sectional study analyzed data from the 2019 and 2024 Korea National Health and Nutrition Examination Survey. A total of 4856 adults aged ≥40 years without chronic obstructive pulmonary disease were included. RSP was defined as FVC < 80% predicted among participants with an FEV1/FVC ratio ≥ 0.70. Pulmonary function and RSP prevalence were compared between survey years using complex sample analyses. Multivariable logistic regression was performed to examine the association between the post-pandemic period and RSP. Results: The prevalence of RSP increased significantly from 2.31% in 2019 to 3.58% in 2024 (p = 0.025). FVC, FEV1, and FVC percent predicted significantly decreased after the COVID-19 pandemic (all p < 0.001), whereas the FEV1/FVC ratio (p = 0.166) and peak expiratory flow (p = 0.671) remained unchanged. After adjustment for demographic characteristics, health behaviors, and metabolic factors, the post-pandemic period remained independently associated with RSP (odds ratio, 1.571; 95% confidence interval, 1.036–2.380; p = 0.033). Conclusions: The prevalence of RSP increased significantly after the COVID-19 pandemic and was accompanied by declines in lung volume-related pulmonary function without evidence of increased airflow obstruction. These findings highlight the importance of strategies targeting metabolic health, obesity, and physical function to preserve respiratory health in the post-pandemic era. Full article

The use of uniform spray volume rates for fruit trees with different canopy sizes is common in orchard spraying with plant protection unmanned aerial vehicles (UAVs), whereas the applicability of Leaf Wall Area (LWA)- and Tree Row Volume (TRV)-based methods to UAV spraying remains insufficiently validated. This study evaluated canopy size-based spray volume optimization and droplet deposition and penetration along the vertical canopy profile in a mountainous Nanguo pear orchard. The results showed that, under a uniform spray volume rate, small canopy trees exhibited significantly higher droplet deposition and ground deposition than large canopy trees, indicating greater potential spray losses. LWA- and TRV-based adjustment reduced the spray volume rate for small canopy trees by 43.0% and 49.0%, respectively, while maintaining comparable deposition in the upper and middle canopy layers. However, deposition in the lower canopy and on abaxial leaf surfaces remained limited, indicating that conventional LWA and TRV methods do not fully account for the top-down deposition characteristics of UAV spraying. Along the vertical canopy profile, finer atomization levels generally favored droplet penetration into the lower canopy, whereas increasing the spray volume rate increased overall deposition but did not significantly improve vertical penetration. Flight speed showed no consistent effect on penetration within the tested range. The results highlight canopy size as a key factor in UAV spray deposition. Canopy size-based variable-rate application can reduce spray volume rate while maintaining effective deposition, but further optimization should consider rotor-induced airflow and canopy structure. Full article

The scientific problem addressed in this study is how a continuous mechanical architecture can maintain stable lettuce handling while improving treatment-medium access to irregular, overlapping leaf surfaces. We formulate this problem as a morphology-informed design and evaluation task. The proposed machine integrates soil removal, a reserved vision-based yellow-leaf detection and root-trimming station, multi-angle disinfection, water–air washing, combined airflow drying, film wrapping, weighing, and boxing modules on a chain-conveyor platform with bowl-shaped fixtures. The evaluation follows a design-to-evidence workflow: lettuce morphology and process requirements are mapped to module geometry; chain, lead-screw, gear, and motor parameters are checked analytically; an application-oriented geometric spray-coverage model tests fixed versus swinging bilateral nozzles; static finite element analysis screens the frame under defined design loads; and prototype assembly verifies spatial compatibility. The covered-surface proxy increased from 7.24% for fixed bilateral spraying to 13.58% for a ±35° swinging case under explicit screening assumptions, while the frame analysis gave 0.0224 mm maximum deformation and 7.30 MPa maximum von Mises stress. These outputs support a preliminary, mechanically feasible platform and a testable explanation for why adjustable spray orientation may improve access to complex lettuce surfaces. They do not constitute measured cleaning, microbial, trimming, drying, packaging, throughput, or reliability performance. Full article

Background: Chronic obstructive pulmonary disease (COPD) and acute myocardial infarction (AMI) frequently coexist and share several biological pathways and risk factors. Although COPD is associated with worse outcomes after AMI, the prognostic value of objective pulmonary function has not been well characterized. The aim of this study was to evaluate the association between airflow-obstruction severity and five-year all-cause mortality after AMI among patients with COPD. Methods: This single-center retrospective cohort study was restricted to adult post-AMI patients (2002–2017) with a background diagnosis of COPD and documented spirometry; therefore, the final cohort represents a selected subgroup of the source COPD-AMI population. Airflow obstruction was categorized according to forced expiratory volume in one second (FEV1) as Mild, Moderate, Severe, or Very Severe (according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD)). The outcome was all-cause mortality during up to five years of follow-up. Results: Among 1594 patients hospitalized with AMI and a COPD diagnosis, 169 patients with available spirometry were included in this selected analytical cohort (mean age 66.76 ± 9.86 years, 76.9% male). During follow-up, 65 patients died, corresponding to an overall five-year mortality rate of 38.5%. Mortality increased progressively across obstruction categories: 19.0%, 33.3%, 40.0%, and 70.8% in Mild, Moderate, Severe, and Very Severe, respectively (p for trend <0.001). In multivariable analysis, adjusted hazard ratios for mortality were: 2.49 (95% CI 0.86–7.24), 3.38 (95% CI 1.09–10.46), and 5.23 (95% CI 1.62–16.89) for Moderate, Severe, and Very Severe, compared with Mild obstruction. Conclusions: Among patients with COPD who survived hospitalization for AMI, more severe airflow obstruction was associated with substantially higher five-year all-cause mortality. These findings support the potential role of spirometry-based risk stratification and highlight the need for integrated cardiopulmonary follow-up after AMI. Full article

To address the technical bottleneck of balancing the wideband noise (100–800 Hz) and aerodynamic performance of multi-blade centrifugal fans in air conditioning indoor units, this paper proposes a “frequency-domain target-driven” parametric design method for micro-perforated silencers. This method began with the precise identification of the 1/3-octave band noise spectrum to determine two noise peak clusters—200–400 Hz and 700–800 Hz—as the target suppression frequency bands. Based on Ma Dayou’s micro-perforated plate theory, a reverse mapping chain of “target frequency range → resonance frequency → structural parameters (hole diameter, perforation rate, rear cavity depth)” was established to enable the quantitative calculation of the silencer’s geometric parameters. Addressing engineering constraints related to manufacturing precision, clogging prevention, and structural stiffness for the theoretically optimal aperture size (0.24 mm), the aperture was adjusted to 1.0 mm through iterative recalculation of the relationship between plate thickness and perforation rate, while maintaining the perforated plate constant k ≈ 1.40 to ensure that the theoretical sound absorption frequency band remained unchanged. Test results show that under semi-anechoic chamber conditions (background noise ≤ 10 dB(A)), the micro-perforated silencer maintains airflow and power without attenuation across all airflow rates; noise peaks in the 200–400 Hz and 700–800 Hz frequency bands are significantly suppressed, and the full-band spectrum tends toward flatness. The average total noise level was reduced by 1 dB(A), and the average peak sound pressure level was reduced by 4 dB(A); the reduction in peak levels was four times that of the total reduction, revealing that the noise reduction mechanism of this method is “frequency-selective resonant absorption” rather than “uniform attenuation across the entire frequency band.” This study provides a quantifiable and reproducible design process for micro-perforated silencers, offering methodological support and engineering references for the development of low-noise compact fan systems in household appliances. Full article

When a shipborne helicopter performs vertical replenishment with external cargo, changes in flight attitude and the combined airflow field may cause the suspended load to rotate, generating torque at the connection assembly. This torque cannot be measured directly during flight, and the interactions among the boom, swivel eye, lifting eye, and cargo frame produce coupled torque components that are difficult to evaluate by simulation alone. Therefore, a real-time torque measurement test system is developed in this study. The system emulates the multi-component connection used in vertical replenishment and can adjust the external load, rotational speed, rotational direction, and offset angle. The tensile force, torque, and rotational speed borne by the swivel eye are measured by a load cell, torque transducer, and tachometer with wireless data transmission. By measuring the torques of a single swivel eye and a double series-connected swivel eye after rotation decoupling, the main torque patterns at the top of the swivel eye are obtained. The results show that the proposed system can measure the torque responses of swivel-eye connections under different loads, offset angles, rotational speeds, and rotation directions. This provides an experimental basis for evaluating the torque transmission behavior of single and double series-connected swivel eyes in shipborne helicopter vertical replenishment. Full article

Background: Early extubation after bilateral lung transplantation (LT) may reduce intensive care unit (ICU) complications, but evidence from heterogeneous real-world cohorts and of its impact on mid-term functional recovery remains limited. Methods: We conducted a single-centre observational study of 149 consecutive adult bilateral LT recipients (February 2016–February 2023). Patients extubated within 24 h were assigned to the early extubation (EE) group (n = 63, 42%) (extubated within 24 h of the end of surgery), while those extubated later comprised the late extubation (LE) group (n = 86, 58%) (extubated beyond 24 h). Multivariable logistic regression identified predictors of late extubation. Outcomes included postoperative extracorporeal membrane oxygenation (ECMO), pneumonia, ICU length of stay, and spirometric parameters at 9–12 months after LT. Results: Higher Lung Allocation Score (LAS; adjusted OR 1.19, 95% CI 1.02–1.38) and intraoperative red blood cell (RBC) transfusions (adjusted OR 1.47, 95% CI 1.04–2.06) independently predicted late extubation. Compared with the LE group, EE recipients required less postoperative ECMO (2% vs. 23%; p = 0.008), had shorter inhaled nitric oxide treatment (7 vs. 17 h; p = 0.006), lower pneumonia rates (8% vs. 23%; p = 0.043), and shorter ICU stays (6 vs. 9 days; p = 0.005). In-hospital and 1-year mortality were similar between groups. At 9 ± 1 months, EE recipients showed better volumetric lung recovery, with higher FVC as a percentage of pre-transplant baseline (78.0% vs. 69.5%; p = 0.048) and higher TLC percentage predicted (77% vs. 68%; p = 0.015). Airflow indices and respiratory muscle strength did not differ. Conclusions: In a broadly inclusive LT cohort, higher LAS and intraoperative RBC transfusion independently predicted late extubation. Early extubation was associated with lower postoperative support requirements and was associated with higher FVC relative to pretransplant baseline, an association that should be interpreted in light of the unadjusted comparison and baseline heterogeneity rather than as evidence of a causal benefit. Full article

In response to issues such as disordered airflow distribution and prominent local hotspots in campus non-standard data centers, this study took a non-standard raised-floor air-supply data center at a university in Hangzhou as the research object, and used a combination of on-site measurements and computational fluid dynamics (CFD) numerical simulation to investigate the optimization of the thermal environment. The temperature and air velocity of the data center were measured using a handheld hot-wire anemometer, and a standard k-ε turbulence model was established on the 6SigmaDC platform (now Cadence Reality DC Design Pro, version 2024.1). Model accuracy was confirmed through grid independence verification with three mesh levels and statistical error metrics (MAE, MBE, RMSE) across multiple measurement zones. The results show that the mean absolute error of temperature does not exceed 0.9 °C in all zones and the mean absolute error of air velocity does not exceed 0.20 m/s, indicating that the model effectively reproduces the airflow distribution and thermal environment of the data center. On this basis, to address the uneven airflow distribution in the underfloor plenum, an optimization strategy was proposed that involved the installation of composite baffles and the coordinated adjustment of variable floor tile openings. Eight representative simulation scenarios were designed, with the coefficient of variation and air supply uniformity index as evaluation indicators. Results indicate that the combined effect of perforated baffles and variable floor tile openings is the optimal strategy, reducing the range of net airflow among air supply outlets from 0.100 to 0.077 m³/s, decreasing the coefficient of variation from 12.8% to 10.8%, and increasing the air supply uniformity index by 10.7%. Whole-room thermal environment verification shows that the optimal scheme reduces the supply heat index (SHI) from 0.42 to 0.35, with an estimated PUE reduction of about 0.03, achieving both airflow uniformity improvement and energy-saving benefits. By improving the cooling efficiency and reducing the PUE, this retrofit strategy contributes to the sustainable operation of small-to-medium-sized campus data centers, supporting energy efficiency and carbon footprint reduction goals under green campus and low-carbon initiatives. Full article

Temperature uniformity in thermostatic chambers is critical for material testing, biological incubation, and precision measurements, as even minor thermal gradients can compromise reliability. However, in chambers designed to avoid airflow disturbances, such as those used in semiconductor fabrication and optical experiments, forced convection and mechanical stirring are often impractical. Consequently, natural convection becomes the dominant heat transfer mechanism, introducing significant nonlinearity, large thermal inertia, and multivariable coupling among multiple heat sources. To address these issues, this study develops a multi-input–multi-output (MIMO) temperature control strategy for a rectangular chamber equipped with eight heating elements (grouped into four channels) and adjustable-angle baffles. The proposed method combines a multi-PID controller array with genetic algorithm (GA)-based parameter tuning using a transfer-function matrix model. Experiments demonstrate that baffle angles below 90° improve spatial uniformity, and the relative grouping of heaters outperforms adjacent grouping in both thermal inertia and correlation. Using GA-optimized PID parameters, the controller maintains steady-state error within ±0.5 °C and reduces settling time by approximately 140 s compared to conventional Ziegler–Nichols tuning. Validated through simulations and experiments, the proposed approach provides a reliable and cost-effective alternative to forced convection for airflow-sensitive applications, achieving superior uniformity and steady-state accuracy. Full article

This study proposes a biomimetic multi-objective optimization framework for airflow distribution design in mine ventilation systems by integrating sensitivity screening with an improved multi-objective sparrow search algorithm (IMOSSA). The design problem is formulated with network-balance, critical branch airflow, fan-boundary, and adjustable-resistance constraints, while theoretical ventilation air power and pressure-drop disturbance are minimized as two conflicting objectives. Resistance-perturbation sensitivity analysis is used to identify high-impact adjustable branches and construct branch-specific search bounds, thereby forming a compact and physically feasible decision domain. Inspired by the foraging and vigilance behaviors of sparrow populations, IMOSSA is employed as a swarm-intelligence Pareto-search engine and integrates three strategies: chaotic opposition-based elite initialization to enhance initial population diversity, density-penalized external-archive guidance to maintain Pareto-front diversity, and stagnation-triggered differential–Cauchy perturbation to improve late-stage escape capability. ZDT and DTLZ benchmark functions verify the computational reliability of IMOSSA; in particular, on the multimodal ZDT4 function, IMOSSA achieves GD, IGD, and HV values of 0.0096, 0.0195, and 0.8479, respectively, indicating strong robustness in complex Pareto-front search. A mine ventilation network case further validates the engineering applicability of the proposed framework. For 13 adjustable branches, the compromise solution reduces model-computed ventilation air power from 313.61 kW to 281.11 kW, corresponding to a reduction of 10.36%, with a pressure-drop deviation of 354.15 Pa; the energy-priority solution further reduces the power to 256.91 kW, corresponding to a reduction of 18.08%. The results show that the proposed biomimetic multi-objective optimization framework can provide computable and interpretable Pareto decision support for airflow distribution design in mine ventilation systems. Full article

To examine the fine-scale structure and evolution of the low-level wind field at a plateau valley airport under different weather conditions, this study analyzes a two-stage wind field event at Xining Caojiapu Airport on 8 April 2022. The analysis uses data from several scanning modes of a three-dimensional Doppler wind lidar (DWL), together with an automatic weather observation system (AWOS), sounding data, and the European Centre for Medium-Range Weather Forecasts Reanalysis v5 (ERA5). The results show that: (1) From 13:25 to 13:45 BJT, downward momentum transport produced low-level wind shear. Under an upper-level jet, post-trough northwesterly flow, and stronger afternoon mixing in the boundary layer, west-northwesterly winds aloft descended and entered the runway area from west to east. Runway 11 responded about 1–2 min before Runway 29. The maximum wind vector difference between the runway ends was 9.42 m s⁻¹, and the maximum wind speed component difference along the glide path was 9.02 m s⁻¹. (2) From 20:15 to 20:35 BJT, the low-level wind field adjusted as a cold front moved into the airport. Strong easterly flow advanced westward from the eastern side as a shallow wedge, with local shear along its upper boundary. Runway 29 responded before Runway 11. The corresponding maximum differences at the runway ends and along the glide path were 6.44 and 4.01 m s⁻¹. (3) The two stages differed in airflow direction, the evolution of the shear interface, and the order of response at the runway ends. Combining the DWL scanning modes with AWOS observations gave a clearer view of the descending strong wind layer, the advance of low-level airflow, local shear, and wind changes over the runway and approach path. This case provides a reference for low-level wind monitoring and operational risk assessment at plateau valley airports. Full article

The application of unmanned aerial spraying systems (UASS) in hilly orchards is challenged by terrain-induced airflow variability, which affects droplet transport and deposition. This study investigated the effects of terrain slope and flight patterns on rotor downwash airflow and droplet deposition using airflow measurements, computational fluid dynamics (CFD) simulations, and field experiments. Adjustable slope platforms (0°, 10°, 20°, and 30°) were used to characterize airflow behavior, while droplet deposition was evaluated under flat, uphill, downhill, and contour-parallel flight conditions, both outside and within citrus canopies. Results showed that increasing slope transformed the downwash airflow from an axisymmetric structure to a downslope-biased asymmetric pattern. Flight patterns significantly influenced deposition distribution. Uphill flight enhanced deposition in upslope and upper-canopy regions, whereas downhill flight increased deposition in rear and lower-canopy regions due to stronger recirculation. During contour-parallel flight, airflow shifted downslope, resulting in higher deposition on the downslope side of the canopy. Under the experimental conditions investigated in this study, the effective spray swath width during single-flight-line operations perpendicular to the contour lines (uphill and downhill flights) was approximately equivalent to the width of one individual tree canopy, whereas contour-parallel flight resulted in a narrower effective spray swath width due to terrain-induced airflow redistribution. An upslope route offset of 0.3–0.5 m improved droplet deposition uniformity between the upslope and downslope canopy regions. These findings provide guidance for optimizing UASS spraying strategies by adjusting flight trajectories, route offsets, and operational parameters according to terrain slope and canopy position. Full article

Background/Objectives: Total nasal reconstruction has long represented a formidable surgical challenge. To date, no universally accepted, evidence-based protocol for nasal reconstruction exists to guide clinical practice. This study introduces a novel technique for comprehensive, three-layer nasal reconstruction. Specifically, the approach entails (1) reconstruction of the nasal mucosal lining using a free radial forearm flap; (2) provision of robust structural support via an exogenous extended framework; and (3) restoration of the external nasal skin using an expanded forehead flap. Methods: Ten patients underwent reconstruction for full-thickness nasal defects, all achieving successful structural and functional restoration. All surgical procedures were completed successfully, with operative durations ranging from 6.5 to 10.5 h. One patient developed an infection involving the rib cartilage graft. Following thorough debridement, the radial forearm free flap healed uneventfully. A second patient experienced postoperative vascular compromise of the flap. Intraoperative exploration revealed inadequate perfusion; immediate microsurgical revision—including adjustment of recipient vessels and/or re-anastomosis—successfully restored flap viability. Results: Primary wound healing was achieved in all patients within 10–22 days. All patients completed a follow-up of 12–36 months (mean: 21.5 months). Both patients and the surgical team rated postoperative nasal aesthetics as satisfactory. Objective functional assessments—including anterior rhinomanometry and peak nasal inspiratory flow—demonstrated no clinically significant impairment in nasal airflow. Conclusions: This surgical strategy for reconstructing the three-layer nasal architecture in patients with total nasal defects represents a rational and clinically viable approach—offering a valuable reference for rhinoplasty surgeons performing such complex reconstructions. Full article

Accurate thermal management is crucial for ensuring the safety, longevity, and performance of lithium-ion batteries, especially in compact embedded systems like USB chargers, power banks, and IoT nodes. Despite extensive research on predictive thermal models and intelligent control frameworks, their implementation in resource-constrained microcontroller-class devices has been limited. Existing strategies in the literature, such as threshold-based or PID logic, cloud-enabled analytics, machine learning models, and observer-based estimators, are often reactive, computationally intensive, or dependent on external infrastructure, making them unsuitable for low-power, standalone applications. This study introduces a novel Scalable Embedded Thermal Intelligence architecture designed for real-time battery thermal regulation in locally executable, without cloud dependency, low-cost platforms. Unlike conventional methods, the proposed system operates entirely on-device using closed-form models implemented on an ESP32 microcontroller. It combines two synergistic algorithms: a static preemptive model that calculates a safe C-rate at startup based solely on ambient and initial battery temperature, and a dynamic disturbance-aware model that monitors temperature rise per SOC step and adjusts airflow or current adaptively without requiring high memory, floating-point units, or supervisory control. The architecture achieves sub-second response times, <7% RAM, and <25% Flash usage, and does not need cloud connectivity, simulation backend, or complex thermal-management infrastructures such as liquid cooling circuits, phase-change systems, or cloud-supervised architectures. The significant contribution of this work is not the introduction of a new electrochemical–thermal formulation, but the effective integration and application of previously validated closed-form thermal predictors on low-cost microcontroller-class hardware, designed for anticipatory battery thermal regulation while adhering to strict computational limitations. Compared to traditional battery thermal management systems using PCM, liquid-cooling circuits, or cloud-based predictive estimators, the proposed approach eliminates the need for complex thermal hardware, fluidic systems, external computing infrastructure and resource-efficient edge operation. This makes the system suitable for deployment in real-world embedded applications like USB-C smart charging cables, compact IoT power banks, and portable medical devices, where form factors, energy efficiency, and cost are critical. The proposed SETI framework offers a firmware-integrated architecture and a firmware-integrated solution that provides a lightweight embedded alternative for predictive thermal regulation for distributed energy systems and miniaturized electronics. Full article