Search Results (74)

The transient pressure rise in occupants’ ears during vehicle door closure remains a key challenge for cabin comfort, but existing simulation methods often lack accuracy or efficiency. This study develops an integrated experimental–CFD–theoretical framework. A high-fidelity vehicle model was constructed from point cloud data and validated against airtightness and door-closure tests. A theoretical model was derived and calibrated using flow hysteresis and fluctuation attenuation coefficients from CFD results. Uncontrolled leakage was represented by distributed circular holes, and the one-way flow through the pressure relief valve was implemented numerically. The refined CFD model reduced the peak-pressure and amplitude errors from 6.33% and 17.62% to 1.75% and 2.66%, respectively. The calibrated theoretical model achieved 93.94% accuracy in pressure amplitude relative to the CFD results, with much lower computational cost. An optimization strategy combining early valve opening with an auxiliary fan at the relief valve reduced peak pressure, amplitude, and pressure change rate by 25.88%, 22.83%, and 41.23%, respectively. By deeply integrating experiments, simulation, and theory with refined modeling of key physical features, this research overcomes the accuracy and efficiency limitations of traditional methods, offering a systematic solution for cabin comfort optimization and advancing forward-development capabilities in vehicle NVH. Full article

Pressure relief valves (PRVs) are key safety components in power transformers, and their discharge performance directly influences pressure mitigation during internal fault events. This study presents a density-based topology optimization approach to improve the internal flow passage of a transformer PRV. Optimization is carried out within a predefined design domain while preserving the original external geometry and functional constraints of the valve. Pressure drop is defined as the objective function, and the Brinkman penalization method is used to model the fluid–solid transition during the optimization process. Based on the optimized topology, a reconstructed valve configuration is developed and evaluated using transient computational fluid dynamics (CFD) simulations. The transient inlet pressure boundary condition is obtained from a 6 MJ transformer arcing experiment to ensure realistic operating conditions. The hydraulic performance of the baseline and optimized designs is compared in terms of cumulative discharged volume, pressure field evolution, velocity distribution, and turbulent kinetic energy. The results indicate that the optimized flow passage reduces internal flow resistance and improves flow organization within the valve chamber under transient conditions. Over a 19 ms discharge period, the cumulative discharged volume increases from 13.219 L to 13.601 L, corresponding to an improvement of approximately 3%. These findings demonstrate that topology optimization can effectively enhance the transient discharge performance of transformer PRVs and provide a basis for improving internal flow design in similar hydraulic safety devices. Full article

The dynamic reliability of steam-turbine governing systems is essential for the safe operation of nuclear power units. As a key regulating and protection component, the reheat valve must complete rapid closure under abnormal operating conditions. This study addresses the closing timeout problem observed in a nuclear reheat-valve oil-motor actuator after domestic substitution, with particular attention to sluggish motion and discontinuous closing at small openings. A coupled hydraulic–mechanical model was then established by integrating the coned-disc spring assembly, hydraulic circuit, cartridge valve, gear–rack transmission, and load resistance based on the mathematical model. The model was used to identify the dominant parameters controlling the fast-closing process, and the optimization strategy was subsequently verified by experiments on an actual actuator platform. The results show that coned-disc spring degradation is a critical source of closing timeout risk. When the equivalent elastic modulus decreases to approximately 195 GPa, the fast-closing time approaches the critical limit of 0.8 s, while further degradation results in evident timeout. The C0 throttling orifice has the strongest influence on the effective closing time by governing the pressure-relief capacity of the working chamber. A coordinated correction strategy, involving coned-disc spring force compensation and throttling parameter adjustment, restores the closing margin, shortens the fast-closing time to 0.78 s, and improves closing smoothness. This work provides the practical guidance for design verification, field commissioning, and domestic improvement of nuclear reheat-valve oil-motor actuator systems. Full article

Pipeline valves play a crucial role in oil and gas exploration, production, transportation, and storage, and a systematic understanding of patent technologies in this field can help identify innovation trends and formulate research and development (R&D) strategies. This study collected more than 5000 pipeline-valve-related patents worldwide from 2006 to 2025, including 2292 invention patents, and adopted a progressive patent analytics approach integrating statistical analysis, network analysis, text mining, and high-value invention patent analysis. The results show that innovation activity in this field has remained active over the past two decades, especially since 2016, when the number of patent publications exceeded 300 in almost every year. China, Russia, the United States, South Korea, and Canada are the major sources of patent activity, with Chinese enterprises and universities making important contributions in terms of patent quantity. However, the analysis of high-value invention patents indicates that representative patents from the United States, Canada, and Russia also have a strong influence. Core innovation directions cover multiple pipeline valve applications in oil and gas extraction, transportation, and storage, with valve control systems and mechanical structures constituting the dominant technologies. The ten identified technological themes and their evolution show that technological innovation in this field has gradually expanded from mechanical improvements in traditional valve bodies, sealing components, and pressure relief devices to diversified directions such as wellhead control, intelligentization, and low-carbon development. The analysis of high-value invention patents further confirms this trend, indicating that pipeline valve technology is being reshaped from a relatively mature mechanical technology field into an integrated technological system that combines mechanical reliability, intelligent control, and other dimensions. Full article

In complex wellbore environments, traditional ball-drop, cable, and electromagnetic sliding sleeve communication methods face reliability problems caused by high temperature, high pressure, complex trajectories, and signal attenuation. This paper presents a pressure-wave-based downhole communication and sliding sleeve activation system. Surface pressure variations generated by pump displacement and pressure relief are used to transmit encoded commands through the wellbore fluid and realize non-contact activation of the downhole sliding sleeve. A wellbore pressure-wave propagation model is established, and the effects of well depth, wellbore diameter, pump displacement, pump-on time, pressure-relief timing, and pressure-relief duration on bottom-hole pressure response are analyzed. A bipolar non-return-to-zero coding strategy combined with a constant-threshold decoding method is proposed to improve signal recognizability and robustness. Simulation results show that for a 5000 m wellbore and a pressure-wave velocity of 1100–1300 m/s, the signal transmission delay is approximately 4.2 s, and the bottom-hole pressure responses induced by pump displacement and pressure-relief valve operation can be clearly distinguished. Laboratory tests at 150 °C and 120 MPa showed that the sliding sleeve achieved a 110 mm stroke and 100% opening ratio in four repeated activation tests. In the field test, three pressure command cycles between 10 MPa and 40 MPa successfully triggered the sliding sleeve, followed by a squeeze test with a displacement of 0.3–0.7 m³/min and a maximum pressure of approximately 60 MPa. The results demonstrate that the proposed system provides a feasible and reliable pressure-wave communication method for downhole sliding sleeve activation in deep and long horizontal wells. Full article

The tension of a marine winch rope depends on the hydraulic pressure supplied to its input hydraulic motor. Traditionally, winches employ a relief valve to control the oil pressure of hydraulic motors. Owing to the inherent control characteristics of the relief valve, this control mode leads to continuous fluctuations in the system oil pressure, causing severe variations in the rope tension during operation. In this study, a direct-acting three-way proportional pressure-reducing valve was used to control the oil pressure of the winch, ensuring that the input pressure to the hydraulic motor was maintained at a set value, thereby mitigating the risk of drastic fluctuations in rope tension during vessel mooring. However, proportional pressure-reducing valve control exhibits shortcomings, such as static nonlinearities, insufficient dynamic response, and poor anti-interference stability, leading to oscillations in the outlet oil pressure and resulting in rope tension fluctuations in the winch. Based on the force and flow balance equations of the proportional pressure-reducing valve and in conjunction with the load characteristics of the winch, a mathematical model of the winch control system was established. An operating point for the pressure-reducing valve was determined, and the control system model was linearized. According to the Bode plot and frequency-domain index analysis, four key parameters affecting the outlet pressure fluctuation of the pressure-reducing valve were identified (valve port flow gain coefficient, viscous damping coefficient, transient hydraulic damping coefficient, and hydraulic spring stiffness). From the perspective of winch operation management, the working parameters of the hydraulic system were adjusted accordingly, and their effects on the four key parameters were analyzed. The results, in combination with model linearization and Bode plot analysis, indicate that appropriately lowering the operating temperature of the hydraulic oil can effectively improve the frequency-domain indices and stability margin of the control system, significantly enhancing the relative stability of the marine winch rope tension. Full article

Leakage identification in district heating networks is challenging because leakage-induced transient pressure waves often overlap with pressure disturbances triggered by routine operations such as valve regulation, pump speed variation, and emergency shut-off. In addition, the scarcity of high-quality labeled leakage samples limits the robustness of data-driven models under small-sample conditions. To address these issues, this study proposes a compact and moderately interpretable framework for multi-condition identification from transient pressure-wave signals, integrating signal preprocessing, handcrafted statistical feature extraction, multiclass ReliefF-based feature selection, and class-wise generative adversarial network augmentation in the selected feature space. A dataset containing four representative conditions, namely leakage, valve regulation, pump speed regulation, and emergency valve shut-off, was constructed using an integrated indoor district heating network testbed. After Hampel-based spike suppression and zero-phase Butterworth band-pass filtering within 0.5 to 300 Hz, time- and frequency-domain statistical features were extracted, and a compact subset was selected by multiclass ReliefF. A class-wise generative adversarial network was then used to augment the training set in feature space, while all evaluations were performed strictly on real samples. The results show that feature-space augmentation improves robustness and generalization under operational disturbances and noise. Using random forest as the representative classifier, Accuracy and Macro-F1 increased from 0.960 to 0.985, while leakage recall improved from 0.920 to 0.980. Further comparisons confirmed that the ReliefF-selected subset outperformed representative alternatives such as LASSO and mRMR. Overall, the proposed framework provides an effective solution for distinguishing leakage events from operational disturbances and offers practical support for online monitoring and intelligent operation of district heating networks. Full article

Background: Public catering is an underexplored One Health interface where structurally complex food-transport equipment may sustain reservoirs of antimicrobial-resistant bacteria. We investigated Escherichia coli from reusable institutional catering food-transport containers, focusing on a difficult-to-clean pressure-relief/ventilation valve compartment. Our objectives were to quantify phenotypic resistance using applied clinical breakpoints, assess inhibitor-synergy outcomes in ESBL confirmatory testing, and contextualize inhibitor-positive isolates by whole-genome sequencing (WGS). Methods: E. coli was isolated from containers sourced from 17 institutions and three central kitchens using ISO 16649-2. Minimum inhibitory concentrations (MICs) were determined by broth microdilution. Extended-spectrum β-lactamase (ESBL) confirmatory testing used cefotaxime/ceftazidime ± clavulanate; inhibitor positivity was defined as a ≥3 two-fold MIC decrease in the presence of clavulanate in isolates meeting CLSI screening thresholds. Inhibitor-positive isolates underwent WGS and CARD-based resistome profiling. Results: Resistance was most frequent to colistin (10, 10.8%), followed by doxycycline (8, 8.6%), florfenicol (7, 7.5%), enrofloxacin (4, 4.3%), and gentamicin (3, 3.2%). Third-generation cephalosporin resistance by clinical breakpoints was uncommon (cefotaxime: 2, 2.2%; ceftazidime: 1, 1.1%). Inhibitor-positive ESBL confirmatory phenotypes occurred in 30 isolates (32.3%), which were sequenced. WGS identified 45 resistance-associated genes across inhibitor-positive isolates but detected no classical ESBL genes; all carried chromosomal ampC/ampH alongside ubiquitous efflux-associated determinants. All WGS isolates belonged to phylogroup A, with serotype O154:H9 (20, 66.7%) and ST5549 (17, 56.7%) predominating. Conclusions: Institutional catering food-transport containers can harbor AMR E. coli, with colistin as the most frequent resistance phenotype and frequent inhibitor-positive ESBL confirmatory profiles that, in this set, were not explained by classical ESBL gene carriage. Integrating phenotype, WGS resistomics, and lineage structure supports targeted hygiene surveillance and risk-informed One Health monitoring in mass catering systems. Full article

Maritime decarbonization has shifted from a long-term aspiration to an engineering and systems-integrated problem under near-term compliance pressure. International regulatory bodies, governments, and a wide array of private-sector coalitions will tighten greenhouse-gas fuel-emission standards from 2028, translating climate targets into enforceable cost signals and accelerating interest in alternative-fuel and retrofit pathways. This review synthesizes the state of the art (SoA) of maritime decarbonization by mapping where technological bottlenecks concentrate along the well-to-wake (WtW) value chain for the main candidate pathways: biofuels, LNG/bio-LNG, hydrogen, ammonia, e-methanol, and electrification, and by benchmarking them side-by-side using a unified framework designed to compare their realizable well-to-wake GHG-reduction potential under maritime operating constraints. Building on that comparative lens, this work aims to connect pathway readiness to the near-term market and regulatory reality, while the alternative-fuel-capable fleet is projected to expand rapidly, creating a structural capability vs. supply gap, in which, for example, ship readiness can outpace low-GHG fuel availability and bunkering rollout. The merged evidence indicates that near-term abatement will be dominated by scalable drop-in biofuels, whereas deep-sea options (ammonia/hydrogen and e-fuels) remain gated by upstream low-GHG production, port infrastructure, and safety/regulatory maturation. Nevertheless, mid-term deployment of low-GHG fuels can act as a system “relief valve”, reducing infrastructure lock-in and accelerating emissions reductions while zero-carbon fuel supply chains scale up. Full article

Thermal runaway events in energy storage power stations exhibit distinct acoustic characteristic signals. Three-dimensional localization of the sound source is of significant importance for achieving precise firefighting interventions. This study proposes an internal fault localization method for power stations based on the acoustic signals from pressure relief valves of energy storage battery packs. By deploying four microphones to capture the acoustic signals from the battery pack pressure relief valves, the spatial location of the faulty pack can be calculated using a three-dimensional localization model trained on a Back Propagation (BP) neural network. The localization accuracy of this model is better than 0.5 m, with the majority of measurement points achieving an accuracy of less than 0.3 m, meeting the requirements for battery pack-level localization. A key advantage of this method is its low sensitivity to time delay measurement errors caused by reverberation and reflections in enclosed spaces. Reliable and stable localization of pressure relief sound sources can be achieved through multiple training sessions within the battery cabin, which facilitates practical deployment. Full article

With the significant increase in the number of motor vehicles in plateau regions, the adaptability and reliability requirements of diesel engines operating under high-altitude and cold conditions have become increasingly critical. In this study, a one-dimensional transient simulation model of the overall engine lubrication system was developed based on a physical experimental prototype. The multiphysics-coupled lubrication system was numerically modeled and analyzed, with particular emphasis on elucidating the influence mechanisms of high-altitude and cold environments on the startup performance of diesel engine lubrication systems. System responses under different ambient pressures (0.88 bar, 0.92 bar, 0.96 bar, and standard atmospheric pressure) and oil temperatures (30 °C, 55 °C, and 100 °C) were systematically investigated. In addition, variations in the opening degree of the oil pump pressure relief valve (closed, 4%, 30%, 60%, and 100%) were incorporated to reveal the governing effects of high-altitude and cold environments on lubrication system startup behavior. The results indicate that under high-altitude and cold conditions, the decrease in oil temperature is the dominant factor and exerts the most significant influence on the steady-state oil pressure and flow rate of the lubrication system. Variations in ambient pressure lead only to an equivalent shift in absolute oil pressure, with negligible effects on relative oil pressure, steady-state flow rate, response time, or filling rate. However, a reduction in atmospheric pressure leads to a decrease in the peak oil flow rate at the outlet of the oil pump. The opening degree of the pressure relief valve exhibits a nonlinear influence on the startup performance of the lubrication system, and significantly decreases the oil filling rate. This study innovatively develops a lubrication system performance prediction model under high-altitude, low-pressure, and low-temperature conditions. Calibrated using vehicle road-test data, the model quantifies for the first time the relative contributions of the three key factors to start-up lubrication performance, thereby providing a clear decision-making framework and prioritized improvement directions for the reliability-oriented design and safety threshold calibration of lubrication systems in high-altitude diesel engines. Full article

With the continuous increase in coal mining depth, rock burst occurs frequently, which poses a serious threat to coal mine safety production. As the key equipment to ensure the stability of coal mine working face, the response characteristics of the hydraulic support safety valve are directly related to the life safety of coal miners and the protection of equipment. To address the problem that the traditional hydraulic support safety valve has a slow response and cannot release pressure rapidly, a new control strategy of a hydraulic support safety valve based on the magnetorheological effect is proposed. The fixed current control strategy and the fuzzy PID strategy based on grey predictive control are studied to improve the response speed and pressure relief efficiency of the safety valve. The effectiveness of the control strategy is verified by AMESim and Simulink co-simulation. The simulation results show that the new control strategy can significantly improve the dynamic response characteristics of the safety valve, shorten the response time and enhance the pressure relief performance. The superiority of the magnetorheological effect safety valve in improving the impact resistance of the coal mine hydraulic support is verified. This study provides a new technical path and theoretical basis for the optimal design of the safety valve of coal mine hydraulic support and the safety protection under rock burst. Full article

Hydraulic transients resulting from sudden pump shutdowns or valve closures can induce severe pressure fluctuations, known as water hammer, which compromise the safety and reliability of water distribution systems. Designing effective surge protection devices requires balancing hydraulic performance with economic feasibility, which naturally leads to a multi-objective optimization problem. This study develops an integrated framework that couples Don Wood’s Wave Plan Method for transient flow simulation with the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) for optimal selection and design of water hammer arrestors. The proposed model simultaneously minimizes total installation cost and a hydraulic penalty function representing deviations in pressure from allowable limits. Decision variables include geometric and operational parameters of different surge protection devices such as air vessels, relief valves, and surge tanks, all constrained by practical hydraulic and physical limits. The resulting Pareto front illustrates the inherent trade-off between cost and reliability, enabling the identification of near-optimal design solutions. This approach provides a comprehensive basis for improving the hydraulic safety of pressurized water systems while maintaining economic efficiency, offering a flexible tool for future optimization and design studies in transient flow management. Full article

Following the Great East Japan Earthquake in 2011, there has been an increased focus on risk assessment and the practical application of its findings to safety enhancement. In particular, dynamic probabilistic risk assessment (PRA) used in conjunction with plant dynamics analysis is being considered for accident management (AM) and operational support. Determining countermeasure priorities in AM can be challenging due to the diversity of accident scenarios. In multi-unit operations, the complexity of scenarios increases in cases of simultaneous disasters, which makes establishing response operations priorities more difficult. Dynamic PRA methods can efficiently generate and assess complex scenarios by incorporating changes in plant state. This paper introduces the continuous Markov chain Monte Carlo (CMMC) method, a dynamic PRA approach, as a tool for prioritizing countermeasures to support nuclear power plant operations. The proposed method involves three steps: (1) generating exhaustive scenarios that include events, operator actions, and system responses; (2) classifying scenarios according to countermeasure patterns; and (3) assigning priority based on risk data for each pattern. An evaluation was conducted using a simple plant model to analyze event countermeasure patterns for addressing steam generator tube rupture during single-unit operation. The generated scenario patterns included depressurization by opening a pressurizer relief valve (DP), depressurization via heat removal through the steam generator (DSG), and both operations combined (DP + DSG). The timing of the response operations varied randomly, resulting in multiple scenarios. The assessment, based on reactor pressure vessel water level and the potential for core damage, showed that the time margin to core damage depended on the countermeasure pattern. The findings indicate that the effectiveness of each countermeasure can be evaluated and that it is feasible to identify which countermeasure should be prioritized. Full article

Background/Objectives: Aortic stenosis (AS) leads to progressive left ventricular (LV) pressure overload, adverse myocardial remodeling, and eventual functional decline. While traditional parameters such as left ventricular ejection fraction (LVEF) may remain preserved until advanced stages, they are insufficiently sensitive to early dysfunction. Global longitudinal strain (GLS) offers improved detection but remains load-dependent. In contrast, non-invasive myocardial work (MW)—derived from pressure-strain loops—offers a more load-independent assessment of myocardial function. This systematic review and meta-analysis aimed to evaluate the effects of transcatheter aortic valve implantation (TAVI) on MW indices in patients with severe AS. Methods: We performed a systematic review and meta-analysis of studies reporting non-invasive myocardial work parameters before and after TAVI (PROSPERO ID: CRD420250517138). Databases were searched through 31 March 2025. Pooled mean differences in global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) were calculated using random-effects models. Sensitivity analyses and meta-regression were conducted to explore heterogeneity and the influence of baseline characteristics. Results: Eleven studies encompassing 1493 patients were included. TAVI was associated with a significant reduction in GWI (−236.67 mmHg% [95% CI: −373.82 to −99.52]; I² = 97.0%; p = 0.002) and GCW (−243.71 mmHg% [95% CI: −407.38 to −80.03]; I² = 97.4%; p = 0.006). No significant changes were observed in GWW or GWE. Meta-regression showed age and baseline LVEF significantly influenced GWE changes, but not other parameters. Conclusions: TAVI leads to a significant reduction in GWI and GCW, reflecting decreased myocardial workload and afterload relief. These findings support the utility of MW indices as valuable tools for assessing myocardial adaptation post-TAVI and potentially guiding clinical decision-making. Full article