Search Results (18,311)

Water-lubricated bearings (WLBs) may exhibit marked friction-induced vibration during low-speed and heavy-load operation as hydrodynamic lubrication becomes insufficient. However, the load dependence of the low-speed operating limit and associated vibration characteristics remains insufficiently understood. In this study, a WLB was tested under specific pressures of 0.28, 0.42, 0.56, and 0.84 MPa during stepwise deceleration from 20 to 6 r/min. A joint three-standard-deviation criterion based on root mean square and peak-to-peak acceleration was used to identify the first measured speed point with marked vibration amplification. The coefficient of friction, time-domain features, spectral energy distribution, envelope characteristics, and FSI-based limiting hydrodynamic capacity were analyzed. The first vibration amplification points occurred at 6, 8, 10, and 10 r/min, respectively, accompanied by audible abnormal sound used only as qualitative corroboration. The onset responses varied from isolated or repeated bursts to pronounced medium-high-frequency impulsive excitation and quasi-periodic low-frequency amplitude modulation. The limiting hydrodynamic capacity calculated at a prescribed eccentricity ratio decreased with increasing load and was lower at the onset condition than at the adjacent pre-onset condition. This vibration-based framework provides an operational method for identifying low-speed operating boundaries related to loads and may support operating-condition selection and early warning of abnormal vibration in WLB systems. Full article

Diffuse volcanic-degassing stations record environmental and instrument-driven variability across minutes to seasons. A flux record alone does not identify which forcing components reach the monitored layer or whether the acquisition chain alters them. We present a local three-channel diagnostic integrating chamber-based soil-gas flux with paired-depth pressure and temperature measurements. The model distinguishes natural, measurement-conditioned, and reported flux; derives frequency-dependent penetration, finite-spacing response, detectability, and sampling effects; and treats pressure-to-flux transfer through a calibratable depth-weighting closure. A reproducible synthetic benchmark uses separate fit, event-free calibration, and held-out test intervals, unequal sensor chains, dry–wet state changes, chamber artifacts, input-measurement stress, and independent environmental and supply perturbations. Across 100 stochastic forcing-and-noise realizations, median quiet-interval $R^2$ was 0.96 for distributed-lag ridge and 0.94 for the frequency-domain flux-row transfer, versus 0.33 for instantaneous regression; full-test medians were 0.36, 0.26, and −0.16. Full-diagnostic median offline retrospective event-window precision/recall were 0.80/1.00; median false supply-candidate and false-any-candidate time fractions were 0 and 0.077. Of seven active transfer components audited at four representative periods, pressure-to-flux, pressure-to-pressure-gradient, and temperature-to-temperature-gradient were robustly recovered; temperature-to-flux recovery was moderate, whereas wind-pressure components were non-separable. These results demonstrate controlled internal consistency, not field validation or source reconstruction. Full article

Commercial operations across trading, import/export, logistics, and technology distribution are being reshaped by the convergence of artificial intelligence (AI), machine learning, multi-agent robotics, and Extended Reality (XR). Small and Medium-sized Enterprises (SMEs) feel this shift acutely: they face the same pressures as their larger competitors; labor shortages, high-SKU inventories that resist tidy categorization, narrow margins, and customer expectations set by Amazon-grade fulfilment, but rarely command the capital or the structured warehouse environments that make industrial automation straightforward. Existing frameworks for AI-driven automation and digital twins have been developed primarily for large-scale industrial settings and do not account for the capital, infrastructure, and organizational constraints specific to SMEs, leaving a gap in SME-scoped integration models. This research addresses that gap by asking how AI-driven robotics and immersive technologies can be integrated to optimize commercial workflows in SMEs operating in dynamic logistics and trading environments. The proposed framework is grounded in Sociotechnical Systems Theory, which treats technology and organizational workflows as jointly designed and mutually adapting, and follows a Design Science orientation in which the architecture itself is constructed as an evaluable artifact rather than a purely descriptive model. Methodologically, the study conducts a narrative synthesis of literature on embodied AI, computer vision, digital twins, VR training, and AR-assisted operations, combined with workflow analysis to identify where SMEs lose the most time and money. These are translated into a four-layer system architecture (perception, cognition, execution, integration) deployed through a four-phase implementation model: needs assessment, digital-twin and VR pre-training, controlled hardware pilot, and AR-supported scaling. The contribution of the study is twofold: conceptually, it brings together several technologies that are often discussed separately in the literature, while focusing specifically on the needs and constraints of SMEs while practically, it proposes a phased roadmap that can help SMEs adopt these technologies gradually, reducing both financial and operational risks. The approach also emphasizes human–robot collaboration rather than replacing human workers. The study does not include experimental validation, it presents a conceptual architecture and implementation roadmap consistent with a Design Science artifact-construction stage that can serve as a basis for empirical testing in real commercial environments. Full article

Environmental interviews, as a soft regulatory measure, serve to promote the fulfillment of corporate environmental responsibilities. However, the underlying mechanisms through which they drive comprehensive ESG (Environmental, Social, and Governance) performance remain underexplored. Using a sample of Chinese A-share listed companies from 2011 to 2024, this study employs a staggered difference-in-differences (DID) model to empirically examine the impact of environmental interviews on corporate ESG performance. Our findings reveal that this soft regulatory pressure significantly improves overall corporate ESG performance. These results remain highly robust to a series of endogeneity checks, including Propensity Score Matching (PSM) and the Heckman two-stage selection model. Mechanism tests reveal that this policy-driven improvement is primarily fueled by structural enhancements in three dimensions: the reshaping of executive green cognition, the strengthening of social responsibility, and substantive pollution reduction. Heterogeneity analysis suggests that the promoting effect of environmental interviews on ESG performance is more pronounced among non-state-owned enterprises and firms facing low financing constraints. This research not only provides empirical evidence for the implementation effectiveness of soft environmental regulations but also offers a practical pathway for corporate green governance. Full article

Background and Objectives: Gastric insufflation may occur during positive-pressure ventilation through a supraglottic airway when airway pressure exceeds the seal pressure. Because pressure-controlled ventilation (PCV) lowers peak inspiratory pressure compared with volume-controlled ventilation (VCV), it is widely assumed to reduce gastric insufflation—an assumption that remains untested in adults. We therefore compared these two ventilation modes during i-gel ventilation. Materials and Methods: In this single-centre, assessor-blinded randomised controlled trial, 68 adults undergoing elective breast surgery under general anaesthesia with an i-gel and neuromuscular blockade, without a gastric drain tube, were allocated 1:1 to PCV or VCV (tidal volume 8 mL/kg of actual body weight). The primary outcome was the postoperative gastric antral cross-sectional area measured by ultrasonography, an indirect measure of gastric gas. The pre-specified primary analysis was a Student’s t-test. Secondary outcomes included peak inspiratory pressure and oropharyngeal leak pressure; gastric insufflation, defined post hoc as a >30% increase in antral area, was assessed as an exploratory outcome. Results: All 68 participants (34 per group) were analysed. The postoperative antral cross-sectional area did not differ between groups (mean difference, PCV − VCV, −23.7 mm²; 95% CI −73.9 to 26.4; p = 0.347; p = 0.568 after adjustment for baseline); the confidence interval excluded the 100 mm² difference the trial was powered to detect. Gastric insufflation occurred in 2/34 (VCV) versus 3/34 (PCV) (p = 1.000). Peak inspiratory pressure and expiratory tidal volume were lower with PCV (all p ≤ 0.002), whereas oropharyngeal leak pressure was similar; in every patient, peak pressure remained below the leak pressure. No adverse events occurred. Conclusions: In adults ventilated through an i-gel at the low airway pressures this device produces, PCV lowered peak inspiratory pressure but did not reduce the postoperative antral cross-sectional area or the incidence of gastric insufflation compared with VCV. Because delivered tidal volume was also lower with PCV, the peak pressure difference is reported descriptively. Within this low-pressure range, and in this selected population, the ventilation mode did not detectably affect gastric insufflation; the trial does not establish equivalence between the modes or extend to higher airway pressures or obesity. Full article

An aero-engine test chamber is a critical facility for aero-engine high-altitude simulation testing, and its structural strength, thermal-deformation compatibility, and axial stability directly affect the safety and reliability of engine tests. To address the coaxiality deviation among the engine inlet, the flow-guiding structure, and the front chamber axis caused by temperature and pressure differences between the front and rear chambers of a large high-altitude test chamber, together with their different support configurations, an overall thermo-structural coupled finite element model of the test chamber was first established. The accuracy of the model was verified through a mesh-independence study and theoretical validation based on thin-walled cylindrical shell theory. The analysis identified an upward displacement of approximately 1.2 mm at the central cross-section of the front chamber in the vertical direction and confirmed that the front-rear chamber transition region is a critical zone for temperature gradients and deformation coordination. A local model was then extracted from the region extending from the rear section of the front chamber central support to the first saddle support of the rear chamber. Thermo-structural coupled analysis was performed on the original double I-beam connecting ring, followed by a comparative assessment of six connecting-ring configurations and parameter optimization of the S2 connecting ring. Finally, the local-model results were compared with those of the overall model to validate the capability of the local model to represent the thermo-mechanical deformation transfer characteristics of the connection region. The results show that, although the original double I-beam connecting ring satisfies the strength requirement, its relatively high stiffness leads to a front-chamber axis deviation of 1.22 mm. Among the six candidate schemes, the S2 connecting ring exhibits the best overall performance because its S-shaped compliant geometry redistributes the local stiffness and weakens the transmission of the thermally induced upward displacement of the rear chamber to the front chamber while maintaining sufficient load-bearing capacity. This study can provide a useful reference for the design of front-rear chamber connection structures in large high-altitude test chambers and for the optimization of similar thermo-structurally coupled load-bearing components. Full article

Granular jamming enables switchable stiffness modulation through vacuum-induced particle confinement and has attracted increasing interest in variable-stiffness robotic systems. However, quantitative characterization of pressure-dependent mechanical behavior remains limited. This study experimentally investigates the relationship between vacuum pressure and structural stiffness using a cylindrical granular-jamming specimen subjected to impact and static three-point bending tests. Coffee granules enclosed within an elastomeric membrane were evaluated under vacuum pressures ranging from 0 to −10 kPa. Under quasi-static loading, beam deflections were converted to equivalent Young’s modulus using classical beam theory, whereas the impact measurements were used to derive an apparent impact-response metric for relative comparison. Both loading conditions exhibited pressure-dependent increases in stiffness accompanied by reduced beam deflection. The static loading configuration showed an approximately linear pressure–stiffness relationship, whereas the impact tests exhibited nonlinear behavior at higher pressure levels, indicating that the apparent mechanical response depends on the loading condition. The results demonstrate that loading conditions influence the measured stiffness characteristics and should therefore be considered when evaluating granular-jamming structures. The presented methodology provides preliminary experimental characterization data that may support the design and evaluation of pressure-controlled variable-stiffness mechanisms for robotic and adaptive mechanical systems. Full article

Continuous gas leakage in thin-walled sealed spacecraft structures produces sustained broadband acoustic-emission (AE) signals from which reliable first-arrival picking is difficult. This study presents an interpretable two-stage workflow that decouples leak screening from regional localization. Experiments used a 500 × 500 × 2.5 mm 3A21 aluminum-alloy plate with eight piezoelectric AE sensors under 0.1 MPa pressure difference. Intact, circular-hole, and slit-leak conditions were each tested three times with a 0.5–1.5 s steady-state window. Leak screening employed the 20–200 kHz mean spectral amplitude (Hann window). A provisional threshold of 0.85, set from three intact records, separated all leak records from intact controls. Regional localization used relative logarithmic RMS amplitudes in an energy-decay plus maximum-likelihood-estimation (ED+MLE) cost function on a 10 mm grid. The equivalent attenuation coefficient, empirically selected as 2.3 m⁻¹ using the 1 mm central-hole calibration case, gave a 10 mm grid error for that calibration demonstration. With this coefficient fixed, the four transfer conditions yielded mean localization errors of 19.6–45.7 mm. The results provide preliminary feasibility evidence for leak detection and regional localization under the controlled laboratory conditions investigated in this study. Further validation requires independent channel calibration, larger background datasets, leak-rate measurements, parameter-sensitivity analysis, and testing on more representative structures. Full article

To address insufficient support for innovative methods under the model-based systems engineering (MBSE) framework during the conceptual design phase of nuclear power equipment, this paper proposes an innovative design strategy based on multi-layer problem decomposition. Three core contributions are presented. First, a five-layer hierarchical problem decomposition framework (Layer 0–4) is proposed and integrated into the MBSE architecture, enabling systematic transition from operational requirements to physical solutions. Second, hierarchical matching rules are established to map problem types at each layer to corresponding innovative tools: knowledge stimulation for Layer 1, DSM and FTA for Layer 2, TRIZ technical contradiction matrix for Layer 3, and TRIZ separation principles for Layer 4. Third, a complete solution set is developed for the HPR1000 reactor core detector removal equipment, including a torque-following control strategy, a cylinder spring pressure roller, and a pulley-based clamping mechanism. Using Arcadia and Capella, full-chain MBSE modeling is completed, and prototype tests demonstrate stable forming performance with a mean profile size of 164.20 mm (SD = 0.559 mm), below the 170 mm design limit. The results indicate that this strategy can effectively guide the innovative design of nuclear power equipment under the MBSE framework during the conceptual design phase. Full article

Rivers are vulnerable to hydrometeorological and climatic pressures, while effective water resources management during low-flow season can be challenging. This paper studies the impacts of extreme hydrometeorological events and climate change on Greek rivers, and presents a framework for the incorporation of these pressures into the Program of Measures (PoMs) of the River Basin Management Plans (RBMPs) for the implementation of the Water Framework Directive 2000/60 (WFD). The final aim is the adaptation to drought and water scarcity. The proposed methodological approach incorporates a process-based model, climate change projections, drought indices and low-flow boundaries, so as to assess the impact of hydrometeorological and climatic pressures on the quantitative quality status of rivers. Then, the quantitative response of rivers under different predicted climate scenarios was examined. Based on the results, a water management plan was adopted and tested regarding its effectiveness, so as to promote evidence-based water strategies. Additionally, comprehensive measures and an operational scheme and adaptations actions for the mitigation of the hydrometeorological and climate related pressures in rivers of Greece were proposed. This operational framework is based on quantitative thresholds that trigger actions and measures for adaptation and can be used by decision-makers and stakeholders as guidelines for mitigation actions. The framework proposed was applied to the Spercheios river basin, which was selected as a demonstration site. Full article

Healthcare waste mismanagement persists because the organisational and communicative dynamics driving erroneous practices remain largely unaddressed, particularly in high-turnover clinical units that concentrate the highest volumes of hazardous waste and operational pressure. Existing training interventions typically address motivational, analytical, or operational dimensions in isolation, lacking a systemic and adaptive framework. This study designs and theoretically validates Maieutic-H, a multilevel training ecosystem integrating narrative and gamified motivational strategies, Video-Based Interaction Analysis of communicative practices, and an AI-driven support system employing an interpretable Random Forest classifier to prioritise corrective actions, embedded within a six-phase adaptive cycle with longitudinal monitoring at one, six, and twelve months. Theoretical validation through comparison with eleven programmes from the literature identifies three recurring, sub-optimal configurations—single-component, parallel-component, and quasi-integrated interventions—none of which combines data-driven prioritisation with interactional analysis to surface operational blind spots. Preliminary qualitative validation against expert interviews showed 93% concordance between operator-perceived priorities and model-generated relevance scores, informing an adaptive recalibration ($\alpha =0.70$) that weights field-derived evidence over the simulated training baseline. The Maieutic-H model offers a scalable, theoretically grounded framework for sustainable behavioural change and regulatory compliance in complex clinical environments, aligning interpretable machine learning with healthcare process engineering. This manuscript presents a model development and theoretical validation study. Evidence on effectiveness will require empirical testing of the full Maieutic-H pathway in hospital pilot studies. Full article

Aiming at the problems of strong model uncertainty, unmodeled perturbation disturbances and unknown maneuvering of space non-cooperative targets in orbital rendezvous missions, an orbit prediction and control method combining active disturbance rejection and model predictive control (ADRC-MPC) is proposed in this paper. Firstly, the relative motion dynamic equations of chaser–target are established under a geocentric inertial coordinate system, and the lumped disturbance including space perturbation and unknown evasive maneuvers of the target is expanded into extended state variable. Secondly, an extended state observer (ESO) is designed to achieve real-time accurate estimation and feedforward compensation of time-varying lumped disturbances, which mitigates adverse influences induced by J2 zonal harmonics, atmospheric drag, solar radiation pressure, and target evasive maneuvers. Thirdly, a constrained MPC strategy incorporating thrust saturation, approach corridor, and collision safety zone constraints is developed. Sufficient conditions for closed-loop input-to-state stability (ISS) are theoretically derived via the small-gain theorem under the given assumptions, which ensures the uniform ultimate boundedness (UUB) of tracking errors. Finally, numerical simulations, comparative benchmarks against conventional MPC and proportional-derivative (PD) control, and Monte Carlo robustness tests are performed. Simulation results demonstrate that the proposed ADRC-MPC framework delivers superior rendezvous precision, stronger disturbance rejection, reduced propellant consumption, and improved robustness against initial state offsets and measurement noises, laying solid theoretical and technical foundations for autonomous orbital rendezvous with space non-cooperative targets. Full article

Background/Objectives: Veterinarians are exposed to substantial psychological strain, including burnout, depressive symptoms, and increased suicide risk. Emotional and ethical challenges, such as managing animal suffering, making difficult treatment decisions, and handling conflicts with animal owners, may compound the pressures associated with demanding working conditions. This study aimed to investigate occupational stressors, working conditions, job satisfaction, and self-reported mental health among veterinarians working in Germany. Methods: An exploratory, quantitative, cross-sectional online survey was conducted among veterinarians working in Germany between August and October 2025. A total of 126 veterinarians completed the questionnaire. Associations between demographic and professional characteristics, working conditions, occupational stressors, and self-reported mental health indicators were analyzed using Pearson’s chi-square tests, Mann–Whitney U tests and Kruskal–Wallis tests. Results: The greatest perceived occupational stress was associated with work–life balance and working hours (mean ± SD: 3.67 ± 1.14), followed by the management of complex medical cases and communication with animal owners. Younger veterinary respondents reported greater stress related to selection of treatment options, whereas older and more experienced veterinary respondents reported greater stress related to administrative workload. Women reported higher stress levels across several domains, including communication with animal owners and the management of difficult medical cases. Veterinarians working more than 40 h per week reported lower satisfaction with work–life balance, while those with more than 28 days of annual leave reported greater workplace comfort. Self-reported stress-related symptoms were frequently indicated in the symptom checklist: 63.5% reported sleep disturbances, 31.7% burnout symptoms, and 26.2% anxiety. Only 19.0% had sought psychological help for work-related stress, and workplace psychological support was available and used by only 3.2% of respondents. Conclusions: The exploratory findings indicate substantial perceived work-related, emotional, and ethical burdens among veterinarians working in Germany. Improved working-time arrangements, administrative support, accessible psychological support, and broader organizational measures may help protect veterinarians’ well-being and long-term job satisfaction. Full article

Background: Intra-abdominal pressure (IAP) has recently been recognized as a new vital sign in critically ill patients. Microwave reflectometry has been proposed as a potential approach for non-invasive IAP measurement. However, systematic investigation on how individual anatomical and geometric factors influence changes in the microwave reflection response of the abdominal compartment is limited. Complementary information regarding illumination frequency and specific absorption rate (SAR) also warrants consideration. Objective: This study aimed to advance the current knowledge on using microwave radar-based sensors in IAP monitoring by studying the most influencing factors. The penetration depth and spot size versus radiation frequency is studied as well. Information on energy deposition due to radio-frequency exposure is investigated too. Methods: Numerical simulations were performed using abdominal models adjusted to represent different IAP levels. Reflection signal features were analyzed in relation to IAP-induced changes, and SAR was calculated using human models. Subsequently, a radar sensor prototype was tested on a benchtop abdominal phantom. Lin’s concordance correlation analysis was used to evaluate absolute agreement between radar-estimated IAP and reference IAP. Additional statistical analyses assessed bias, precision, concordance, and risk levels. Results: Sagittal abdominal diameter was the dominant factor affecting the microwave reflection response. Reflection amplitude showed a periodic trend consistent with abdominal displacement corresponding to multiples of half-wavelength values of the applied electromagnetic waves. Numerical SAR simulations showed increasing SAR with frequency while remaining below the applicable exposure limits under the investigated conditions. The radar sensor showed a bias of 0.43 mmHg and a precision of 2.55 mmHg. Concordance analysis among the paired changes remaining after application of the predefined exclusion criteria showed agreement in the direction of IAP change. Conclusion: The present study should be considered a preliminary proof of concept. Clinically, the technology is currently more suitable for early warning and trend monitoring than for precise absolute IAP measurement, and it does not yet replace standard intravesical measurements. Its ability to support clinical decision-making, including guiding fluid therapy, requires prospective validation in patients. Full article

The coarse-grained heat-affected zone (CGHAZ) is a critical brittle region in welded reactor pressure vessel steels, and phosphorus segregation at prior-austenite grain boundaries can further impair its low-temperature toughness during long-term service. Although phosphorus-induced embrittlement has been established for SA508-4N base metal, the quantitative relationship between grain-boundary phosphorus segregation and the ductile-to-brittle transition temperature (DBTT) in the CGHAZ—and the role of its distinct bainitic microstructure relative to the base metal—remains insufficiently understood. Here, a CGHAZ was simulated in P-doped SA508-4N steel and thermally aged at 500, 530, and 560 °C to establish different equilibrium segregation levels. Optical metallography, Vickers hardness testing, Charpy impact testing, and Auger electron spectroscopy were used to correlate microstructure, hardness, DBTT, and grain-boundary phosphorus concentration. As the aging temperature increased from 500 to 560 °C, the grain-boundary phosphorus concentration decreased from 21.40 to 18.46 at. %, while the DBTT decreased from −53 to −91 °C. The nearly unchanged hardness excludes hardening as the principal cause, demonstrating that the toughness variation is governed predominantly by non-hardening embrittlement associated with phosphorus segregation. The DBTT exhibited a strong positive linear correlation with the equilibrium grain-boundary phosphorus concentration. Moreover, at a comparable prior-austenite grain size, hardness, and phosphorus segregation level, the CGHAZ showed a higher DBTT than the base metal, which is attributed to the lower crack-deflection capability of tempered bainite compared with tempered martensite. These results fill the quantitative gap linking phosphorus segregation to CGHAZ embrittlement and provide a basis for assessing the long-term integrity of SA508-4N welded joints. Full article