Mechanical and Aerospace Engineering

PurposePolymeric heart valves (PHVs) offer the potential to combine the durability of mechanical valves with the favorable hemodynamics of bioprosthetic valves; however, establishing clear relationships between polymer properties and valve-level function remains a key challenge. This study evaluates polycarbonate-based polyurethanes as candidate scaffold materials for polymeric mitral valves through a multiscale structure–function approach.MethodsTwo aromatic polycarbonate-based thermoplastic polyurethanes, Carbothane AC-4095A (CB95-AC) and QuadraSil ARCS 90A (Qsil), were characterized using rheological, mechanical, and spectroscopic analyses. Trileaflet valve scaffolds were fabricated and evaluated using particle image velocimetry (PIV), pressure–flow measurements, and accelerated wear testing (AWT) up to 50 million cycles. Preliminary in vivo performance was assessed following implantation of a CB95-AC valve in an ovine model.ResultsQsil exhibited higher solution viscosity, lower storage modulus, and improved elastic recovery, indicating a more compliant response, whereas CB95-AC demonstrated greater stiffness and tear resistance. Both materials maintained stable valve function, with preserved projected orifice area and repeatable pressure waveforms after AWT. PIV analysis showed physiologic pulsatile inflow and intraventricular vortex formation for both valves, with Qsil producing slightly broader vorticity patterns and CB95-AC exhibiting more localized flow structures. Evaluation of the CB95-AC valve in vivo demonstrated preserved transmitral inflow with low pressure gradients and no evidence of obstruction.ConclusionPolycarbonate-based polyurethanes provide promising performance as polymeric mitral valve scaffolds, with material-dependent differences influencing leaflet mechanics and flow organization while maintaining structural integrity during comparative accelerated wear testing. These findings provide a multiscale framework for evaluating associations between polymer properties, mechanical behavior, and valve-level performance in next-generation polymeric and hybrid tissue-engineered heart valves.

Accurate identification and enumeration of microscopic particles are important for microfluidic analysis, electrokinetic studies, and microscopy-based characterization of microfabricated systems. This study presents an optimized Hough Circle Transform (HCT) workflow for automated particle detection, sizing, and counting. Gold interdigitated electrode arrays (IDEAs) were fabricated on wafer substrates to generate electroosmotic flow, and 3 μm and 5 μm polystyrene microbeads were used as model particles. The final workflow incorporates parallelized multicore parameter optimization and composite statistical metrics based on detection accuracy and frame-to-frame standard deviation, enabling a small manually counted calibration set to be converted into locked detection parameters. In the final validation workflow, 10 manually counted calibration frames were used to optimize HCT parameters for each of four scenarios, and the locked parameters were then validated on 50 new frames per scenario (200 validation frames total) with two independent annotators. Mean validation success rates were 85.1% for 3 μm beads, 90.0% for 5 μm beads, 86.1% for 3 μm beads in mixed suspensions, and 87.2% for 5 μm beads in mixed suspensions, corresponding to object-level error rates of 17.9%, 10.9%, 19.9%, and 13.7%, respectively. Compared with the historical Generation I serial workflow, the optimized workflow reduced parameter-selection time from 24-48 h to 1-2 h, and the runtime image-processing time was approximately 45 ms per frame during offline analysis. These results show that parameter optimization is essential for robust HCT-based particle enumeration and that the workflow provides a practical analytical tool for microfluidic device characterization and electrokinetic experiments.

The rising demand for hydrogen calls for improvements in the efficiency of liquid alkaline water electrolysers (LAWEs), which can be fulfilled by advanced electrodes or separators. Nevertheless, they also intensify hydrogen crossover and safety concerns, thus mandating efficient mitigation strategies. Here we studied the correlation between cathodes and hydrogen crossover behaviours and mitigated safety risks by designing a gas recombination catalyst (GRC). We attribute the elevated hydrogen crossover associated with platinum-based cathodes to their preferential utilization for the hydrogen evolution reaction that creates elevated hydrogen supersaturation, as evidenced by direct measurements of dissolved hydrogen concentration. Varying the placement of platinum layers relative to the cathode–separator interface also supports this conclusion. The implementation of a GRC reduces hydrogen crossover by 95% without affecting LAWE performance and functions for over 1,000 h at 1 A cm−2. This study provides insights into hydrogen supersaturation and the crossover mechanism, as well as offering a promising pathway to enhance the efficiency and reliability of alkaline water electrolysis.

As research and industrial interest in anion-exchange membrane water electrolysis (AEMWE) grows, there is an increasing need for reliable baselines and cross-lab validation of results. The wide variety of material sets and operating conditions under consideration for AEMWE has thus far limited efforts for standardization. In this study, round-robin testing was conducted in deionized water and KOH-based supporting electrolyte by 5 institutions from academia, national laboratories, and industry to provide baseline performance data and identify sources of cross-lab variability. Baseline membrane electrode assemblies were fabricated with commercial catalysts, membranes, and transport layers using standard techniques and tested using reagent-grade electrolytes, aiming for accessibility rather than state-of-the-art performance. From all tests, the average voltage at 1 A/cm2 was 2.72 ± 0.17 V and 1.87 ± 0.03 V in deionized water and 0.1 M KOH, respectively. The maximum in-house and cross-lab variations at this current density were 118 mV and 476 mV in water and 60 and 88 mV in 0.1 M KOH. The KOH purity, station contamination, and temperature control were identified as possible factors affecting performance between labs, with in-house specific variation attributed to sample-to-sample differences in fabrication, cell assembly, and station contamination. This work provides a commercial baseline for the field and highlights the need for improved standardization and reproducibility in AEMWE research.

PurposeEarly detection of right ventricular (RV) dysfunction is essential in pulmonary arterial hypertension (PAH) but remains challenging using conventional echocardiography. This study investigates the feasibility of a noninvasive, physics-based framework using three-dimensional (3D) echocardiography that integrates myocardial strain and volumetric flow analysis to characterize RV mechanical performance across stages of PAH.MethodsA prospective pilot study (N = 15) enrolled healthy controls, PAH patients with preserved RV size, and PAH patients with RV dysfunction. Deformation was evaluated by principal strain analysis and by conventional (longitudinal, circumferential) components. Hemodynamic metrics included hemodynamic forces and energetic properties that were derived using a physics-informed volumetric echocardiographic particle image velocimetry (V-Echo-PIV) method applied to contrast-enhanced acquisitions.ResultsDeformation analysis revealed that longitudinal strain was significantly reduced even in PAH patients with preserved RV dimensions, while second principal (secondary) strain showed a distinctive sign reversal, indicating a paradoxical systolic lengthening, early in the disease. The analysis of hemodynamic forces showed a marked reduction in systolic propulsion across all PAH stages. In contrast, energetic abnormalities were predominantly observed at later stage of the disease.ConclusionsThe integration of 3D myocardial strain with fluid dynamics provides a comprehensive physiological assessment of RV remodeling. While strain and systolic propulsion appear as sensitive markers for early dysfunction, diastolic energetics may support disease staging. This noninvasive framework shows promise for early detection and longitudinal monitoring of PAH patients.

Integrating advanced air mobility (AAM) into existing airspace will require substantial research and development regarding how diverse vehicles can operate cooperatively and safely in congested environments. Effective integration of AAM will hinge on the ability to develop robust, alternative traffic flow management techniques tailored specifically to the unique demands of AAM. This research introduces an air traffic management simulation framework for AAM operations, implemented in the open-source platform BlueSky. The framework characterizes airspace through demand models and vertiport networks and integrates high-fidelity vehicle performance and source noise models, enabling a deeper evaluation of flow management methods and the connection between noise and aircraft operations for mixed fleets of unique AAM vehicles. Performance is assessed through metrics of efficiency, safety, energy usage, and community noise exposure. The framework is exercised for an example AAM airspace design in the Dallas–Fort Worth region, incorporating a departure scheduling algorithm and a conflict resolution method based on the speeds of aircraft in conflict. Results demonstrate that the speed-based algorithm resolves over 90% of arrival conflicts across all demands, though it increases energy use, particularly for faster aircraft. Results also show a reduction in community noise exposure with the application of the speed-based method for mixed aircraft fleets.

We are a student-led research team dedicated to bridging the gap between natural flight and modern engineering by studying the complex aerodynamics of flapping wings. Our project focuses on evolving our quadflapper and novel prototypes into high-performance aerial vehicles that challenge the efficiency of traditional propeller drones.

The UCI Rocket Project Solids (RPS) undergraduate team presents their 2025-26 design and manufacturing process for their latest rocket: Light Fury. RPS operates on a one-year design cycle while implementing new design aspects to expand the depth of the team's engineering capabilities. This APCP-based solid propellant rocket features a 5U Cubesat payload with a deployable rover and UCI's first-ever active control airbrake system, alongside custom-manufactured carbon fiber and fiberglass airframes and fins. Light Fury is set to compete in the 2026 International Rocket Engineering Competition in Texas, where the rocket must reach an exact 10,000ft. apogee achieved by the airbrake system. This poster details their progress throughout the 2025-26 year, from initial design choices, testing procedures, static fires, and launches on their testbed rocket: Night Fury.

Significant variations in measured overflight noise are observed from airport monitor networks, even for similar aircraft flying comparable operational procedures. Operational factors, including aircraft configuration, acceleration and deceleration procedures, thrust profiles, and associated environmental factors, can impact noise. To assess these impacts, operational Automatic Dependent Surveillance–Broadcast surveillance and weather data were associated with noise monitor recordings for a 3-year period at Seattle-Tacoma and John Wayne International Airports for Boeing 737-800, Boeing 737-700, and Airbus A320 aircraft. The impact of flight procedures on noise observations is assessed by evaluating flight profiles by airline to investigate the impact of differences in departure and arrival procedures. It was observed that aircraft weight and thrust correlate positively with noise on departure. At John Wayne Airport, there is evidence that thrust variations can result in large differences in noise near the airport, while procedural differences, such as a steeper initial climb seen at both airports, can reduce noise levels at further distances. Noise on arrival was observed to correlate more closely with airspeed and shows evidence of being dependent on aircraft flap configuration.