最新刊期
卷 59 ， 期 7 ， 2025
- 摘要：Given that existing intelligent fault diagnosis methods for rotating machinery often lack generalizability and are typically limited to specific models, structures, operating conditions, measurement points, and load scenarios, a universal fundamental model for intelligent fault diagnosis tailored to rotating machinery is developed. By mining massive volumes of state monitoring data from various types of rotating machinery, a multi-source data structure with a multi-scale adaptive alignment method is proposed. A multi-level state fusion intelligent diagnosis model is constructed, and a universal fundamental model with strong applicability to typical rotating machinery is established. Additionally, a method for individualized customization and adaptation of the diagnosis model is introduced. The proposed method is validated on extensive state monitoring datasets for rotating machinery. Experimental results show that the universal intelligent diagnosis model can directly detect anomalies in unknown measured equipment, achieving an overall diagnosis accuracy of 88.5% without any supervised fine-tuning. With minor fine-tuning using a small amount of measured data, the model rapidly adapts to new equipment and achieves a diagnosis accuracy of up to 98.6%. Furthermore, the proposed data preprocessing method enables cross-equipment signal amplitude normalization while preserving the relative amplitude distribution between healthy and faulty states within the same equipment, effectively retaining key amplitude-based feature differences. These findings demonstrate the strong engineering potential of the proposed method and its promise for widespread application in real-world industrial scenarios.关键词：intelligent fault diagnosis;general foundation model;rotating machine;customized adaptation303|48|0更新时间：2025-07-09
- 摘要：To overcome the fluctuations in health monitoring indicators of axle box bearings in high-speed trains due to variations in operating lines and speeds, and to address the difficulties of traditional threshold methods in monitoring bearing health based on a unified standard, a threshold adaptive intelligent health monitoring method for axle box bearings under multiple operating conditions is proposed. First, by analyzing the Spearman correlation coefficients between features and rotational speed, the health indicators of the bearings at multiple operating speeds are normalized to eliminate fluctuations caused by changes in train speed. This enables the automatic adaptation of monitoring thresholds to the train's operating conditions. Next, an improved Isolation Forest algorithm based on random feature subsets and principal component direction segmentation (SPCD-iForest) is established. This algorithm uses the collaborative information provided by multidimensional features to classify the normal and faulty states of the bearings along the principal component direction of the data, enhancing the computational efficiency of anomaly detection while maintaining monitoring accuracy. Finally, the proposed intelligent health monitoring method is validated using data from line tests of train axle box bearings. Results show that the proposed method eliminates the impact of changes in train operating conditions on the health indicators of axle box bearings. The output anomaly factor is a dimensionless indicator ranging from 0 to 1, effectively reflecting changes in the health status of the axle box bearings. Compared to the TADS trackside acoustic detection method, it can detect bearing faults more than 10 days in advance and is adaptable to monitoring and diagnostic needs across different train speeds and lines. This method is significant for ensuring the safe operation of high-speed trains and enabling predictive maintenance for axle box bearings.关键词：high-speed trains;axle box bearings;health monitoring;isolated forest;feature normalization148|26|0更新时间：2025-07-09
- 摘要：To address the limited interpretability and reliability caused by the unknown internal decision-making and inference processes of one-dimensional convolutional neural networks (CNNs) in mechanical fault diagnosis, a similarity connection between signal analysis and neural networks is established from the perspective of feature extraction. By extracting the weights of the convolutional layers in the neural network and observing the variations in time/frequency domain features as the network layers change, this study reveals the intrinsic feature extraction behavior of neural networks. Experimental test data and publicly available bearing data from Case Western Reserve University are used for validation. The results indicate that the convolutional kernel can be equivalent to a finite impulse filter, and the max pooling layer can meet the non-linear requirements of neural networks for simple binary classification tasks, therefore not requiring an activation function in the convolutional layer; the neural network is capable of incrementally increasing frequency resolution layer by layer to identify frequency components close to theoretical fault characteristic frequencies, exhibiting similarities to Fourier transforms. When the spectral range is ultimately decomposed to 1 to 3 times the fault characteristic frequency, the identification task is better accomplished. This study can provide new ideas and methods for revealing the “black box” mechanisms and interpretability of convolutional neural networks.关键词：interpretability;one-dimensional convolutional neural networks;Fourier transform;fault diagnosis;frequency domain148|38|0更新时间：2025-07-09
Special Topic Big Data Intelligent Fault Diagnosis and Prediction
- 摘要：To address the limitations of existing anti unmanned aerial vehicle (anti-UAV) technologies, which only focus on interfering with and intercepting UAVs themselves, resulting in a “symptomatic rather than fundamental” solution, a rapid search and detection technology aimed at non-cooperative UAV ground stations and operators is proposed. First, the direction of the non-cooperative UAV ground station is determined using a time-modulated array antenna signal direction-finding method. Then, based on this directional information, perspective projection is employed to calculate the projected size of the ground station operator in the UAV-mounted visual device. Finally, a lightweight target detection network is reconstructed, and a network selection mechanism assisted by target projection size information is implemented to achieve rapid operator detection. Simulation and experimental results demonstrate that the proposed technology enables fast search and detection of ground stations and operators. Specifically, the average single direction-finding time on the UAV platform is 9.67 ms, with an average direction-finding error of 1.08°. The image detection frame rate for operator targets is improved by an average of 52.98%, while the reconstructed target detection network reduces the parameter count by 59.6% and floating-point operations per second by 37.7% on average. The proposed technology provides a novel approach and methodology for anti-UAV measures.关键词：anti unmanned aerial vehicle;signal direction finding;time-modulated array antenna;perspective projection;rapid detection38|31|0更新时间：2025-07-09
Special Topic Academic Papers of the 27th Annual Meeting of the China Association for Science and Technology
- 摘要：Through three-dimensional steady-state numerical simulations and orthogonal experimental design, this study systematically investigates the influence of anti-swirl ribs with varying structural parameters on flow characteristics and axial force within turbopump balance pistons. The flow domain of the turbopump balance piston in a liquid rocket engine is selected as the research object for 3D steady-state numerical simulation, revealing the impact of anti-swirl ribs on internal flow patterns. An orthogonal experimental scheme is designed to evaluate the differential effects of rib width, height, and quantity on axial force. The introduction of anti-swirl ribs significantly alters the internal flow characteristics of the turbopump balance piston. After implementing anti-swirl ribs, the internal flow patterns become more complex, with increased vortex generation in the rotor-stator disk gaps that enhances energy dissipation. This subsequently modifies the internal pressure distribution, leading to notable changes in axial force-achieving up to a 14.3% reduction in axial force within the leakage channel. Among the selected structural parameters of anti-swirl ribs, their influence on axial force, ranked from highest to lowest, is as follows: width, height, and quantity. The first two parameters show ranges of 4.6 times and 3.5 times the corresponding results for the quantity of anti-vortex ribs, respectively. Through optimized anti-swirl rib parameter design, this study improves the operational characteristics of balance pistons, thereby enhancing turbopump stability. The findings provide valuable references for performance optimization of liquid rocket engine turbopumps.关键词：turbopump;balance piston;axial force;swirl brake37|27|0更新时间：2025-07-09
- 摘要：To investigate the liquid acquisition performance of the screen channel liquid acquisition devices (SCLADs) installed in cryogenic propellant storage tanks, a three-dimensional outflow model of a screen collection channel integrated with the tank wall is established for liquid hydrogen tanks. The porous step model is employed to describe the pressure loss characteristics of the screen penetration. The velocity and pressure distributions during the liquid acquisition process are calculated, revealing the influence of wall distance, channel width, and channel curvature on the SCLAD's performance. The results show that the presence of the tank wall induces pressure loss on the outer side of the screen, with the pressure drop increasing along the flow direction, thereby affecting the velocity distribution and liquid acquisition efficiency in the upstream and downstream sections of the channel. Variations in the wall distance (d) and channel width (W) both impact the device's performance. A higher W/d ratio increases the pressure loss on the outer side of the channel, reducing bubble breakthrough risk and enhancing upstream liquid acquisition while slightly compromising downstream performance. However, an excessively large W/d ratio decreases the total liquid acquisition volume, with an optimal W/d ratio of around 10 for maximum efficiency. In the absence of gravity, channel curvature has negligible effects on liquid acquisition. In the presence of gravity, the influence of curved channels depends on the effective length hg in the direction of acceleration, with smaller hg values yielding better acquisition stability.关键词：cryogenic propellant;liquid acquisition device;screen liquid collection channel;wall distance;liquid acquisition performance24|21|0更新时间：2025-07-09
-
Multi-Objective Optimization of Flow and Heat Transfer in Matrix Cooling Channels with Tapered Holes
摘要：To reduce flow resistance in internal cooling channels, accelerate the local flow of cold air, and enhance vortex disturbances near rib walls for improved heat transfer, a novel matrix cooling structure for turbine blades is developed by incorporating tapered holes in the rib plates. This study constructs a new type of tapered hole rib matrix cooling channel and conducts a multi-objective optimization design. Numerical simulations of the Reynolds-averaged Navier-Stokes equations (RANS) are performed to investigate the effects of the rib spacing-to-width ratio (k), rib angle (α), and cone angle (β) on flow and heat transfer. A response surface prediction model for the Nusselt number (Nu) and friction factor (f) is established, and its effectiveness is analyzed. The non-dominated sorting genetic algorithm Ⅱ(NSGA-Ⅱ), combined with the technique for order preference by similarity to ideal solution (TOPSIS), is used to optimize and identify the best structure within the studied parameter range. The average errors of the response surface prediction models for the two objective functions are 0.967% and 2.182%, with maximum errors of 3.063% and 4.517%, respectively. Under conditions of Re=5 000 and q=2 000 W/m2, the optimal structural parameters are found to be k=2.461, α=54.774°, and β=1.415°. The errors in the optimized results for Nu/Nu0, f/f0, and F are 0.32%, 3.38%, and 1.51%, respectively, indicating the effectiveness of the optimization method. The tapered holes facilitate the generation of downstream vortices, effectively reducing flow resistance while enhancing heat transfer uniformity. Compared to the original structure, the optimized design achieves a 6.37% increase in Nu/Nu0, a 17.69% decrease in f/f0, and a 13.43% improvement in the overall heat transfer coefficient F, resulting in enhanced cooling performance.关键词：matrix cooling;turbine blade;multi-objective optimization;conical hole30|41|0更新时间：2025-07-09 - 摘要：To address the challenges of quantifying the contact thermal resistance caused by microscopic interfacial morphology in finite element thermal analysis of ball screw pairs and the variation of convective heat transfer coefficients under dynamic operating conditions, an equivalent loading method for contact thermal resistance in ball screw pairs is proposed and a thermal analysis model incorporating corrected contact thermal resistance and convective heat transfer coefficients is established. Based on the MB fractal theory, the contact thermal resistance between components of the ball screw pair is calculated, and the thermal boundary conditions of the screw under different operating conditions are determined. Temperature field simulation results for a specific screw model show that when contact thermal resistance is considered, the temperature differences between the screw/nut and nut/worktable interfaces increase across all operating conditions, with the maximum difference rising from 1 ℃ to 7.2 ℃. After accounting for convective heat transfer coefficient variations, the overall temperature rise of the screw decreases, and a 4.8 ℃ temperature reduction is observed at the nut/worktable interface. Experimental measurements of the worktable temperature are conducted to validate the simulation model. Compared with experimental results, the calculation errors for temperature rise at the nut node decrease from 29.5% to 3.63%, and at the worktable node from 46.8% to 5.6% after implementing the proposed corrections. The developed thermal analysis model demonstrates applicability for temperature prediction in ball screw pairs under varying rotational speeds.关键词：ball screw pair;contact thermal resistance;convective heat transfer;finite element analysis20|17|0更新时间：2025-07-09
- 摘要：To reveal the influence of hold depth on the sealing performance and dynamic characteristics of hole-pattern damper seals, and to explore the optimal hold depth scheme, this paper employs an unsteady multi-frequency perturbation numerical method to investigate the leakage and dynamic characteristics of hole-pattern damper seals at different depths. First, the accuracy of the numerical method is validated by comparing the leakage amounts and dynamic characteristic coefficients of hole-pattern damper seals at three different depths with experimental data. Then, the leakage amounts of hole-pattern damper seals with three different diameters (D=2.0, 3.175, 5.0 mm) and continuously varying depths (depth-to-diameter ratio Ar=0.1—1.25) are calculated and analyzed. Finally, the dynamic characteristic coefficients, chamber dynamic pressures, and vortex velocity developments of the seals under two types of inlet pre-rotation (μ0=0, 0.5) and five different depths (H=0.5, 1.0, 1.9, 3.3, 6.6 mm, D=3.175 mm) are evaluated. Numerical results indicate that the depth-to-diameter ratio Ar is a key geometric parameter affecting the leakage characteristics of hole-pattern seals. From the perspective of sealing performance, Ar=0.4—0.5 represents the optimal hole depth scheme, at which the leakage amounts for different diameters reach their minimum. In terms of dynamic stability, hole-pattern damper seals with smaller depths exhibit better dynamic stability. When determining the optimal hold depth, it is necessary to consider the impact of contaminant deposition and corrosion wear, avoiding excessively small depths (H≥1.0 mm).关键词：hole-pattern seal;leakage characteristic;rotordynamic characteristic;the ratio of hole depth and hole diameter;multiple-frequency whirling numerical simulation24|27|0更新时间：2025-07-09
- 摘要：In order to meet the demand for real-time fatigue life tracking in wind farms and to reduce operation and maintenance costs, a novel high-order peak-valley identification method is proposed to address the insufficiency of real-time performance in traditional stress cycle identification algorithms. This method identifies peak-valley sequence data of wind turbine loads, introducing the concepts of half-cycles and high-order interval cycles to achieve fast and accurate fatigue life assessment. The research results indicate that the high-order peak-valley identification method achieves better computational accuracy than the variable range mean method and is comparable to the rain flow counting method. Furthermore, its computational response speed far exceeds that of the rain flow counting method, with a computational acceleration ratio of over 5 times compared to performance without this method for each wind turbine. The high-order peak-valley identification method is applied to analyze the tower thrust and main shaft torque data of wind turbines and to calculate the equivalent fatigue load and accumulative fatigue damage. As time increases, damage grows rapidly in the early stages and then gradually slows down, with significant differences in the growth rates of cumulative fatigue damage among different wind turbines. The high-order peak-valley identification method can effectively reduce the computation time for fatigue life assessment, which is significant for improving the safety and economic efficiency of wind farms.关键词：wind turbines;fatigue life;stress cycles;high-order peak-valley identification method;rainflow counting method27|18|0更新时间：2025-07-09
- 摘要：To investigate the knock suppression methods for high compression ratio methanol engines, an experimental study is conducted on a single-cylinder naturally aspirated spark-ignition methanol engine with a compression ratio of 15∶1, focusing on the impact of injection modes on knock characteristics under stoichiometric mixed gas conditions. First, the influence of load, ignition timing, and air-fuel ratio on knock characteristics is explored under the intake port injection mode. Second, the effect of injection timing on knock characteristics is examined under the direct injection mode. Finally, the suppression effect of multiple injection strategies on knock is analyzed under wide-open throttle conditions. The results indicate that in the intake port injection mode, the methanol engine experiences knock combustion at medium to high loads, with a strong knock phenomenon characterized by low frequency and high intensity, reaching a maximum knock intensity of 8.42 MPa at an indicated mean effective pressure (pi) of 0.7 MPa. In contrast, under the direct injection mode, the knock phenomenon is significantly suppressed, with the maximum knock intensity dropping to 0.43 MPa when pi is 0.91 MPa. A reasonable two-injection strategy further reduces knock intensity compared to a single injection strategy while maintaining a high pi. This study confirms the effectiveness of combining direct injection with a two-injection strategy in suppressing knock phenomena in high compression ratio methanol engines, providing theoretical basis and data support for the development and application of methanol engines.关键词：methanol;high compression ratio;knock characteristics;knock suppression;injection strategy25|11|0更新时间：2025-07-09
- 摘要：In order to further enhance the operational flexibility of coal-fired units and to realize the thermo-electric decoupling of coal-fired units from the power system, the optimal design of heat storage heat exchanger in coal-fired molten salt coupling system is studied. Based on the structural characteristics of a novel modular molten salt thermal energy storage heat exchanger and field measurement data from actual operating conditions, the heat transfer coefficient on the molten salt side is calculated and the flow and heat transfer characteristics of the steam-water system are analyzed. Utilizing the flow network system method, the steam-water tube bundle is divided and a flow distribution and pressure drop calculation model is established. Actual operational data measured during the molten salt pump startup condition are compared with the total pressure drop obtained from the program calculations, resulting in a relative error of 2.13%, which verifies the reliability of the calculation model. The pressure distribution, flow distribution, outlet steam temperature, and pipe wall metal temperature under design conditions of the steam-water system are calculated and analyzed, along with a study on flow instability when thermal load disturbances occur. The results indicate that, under design conditions, when the molten salt pump is not started, the working fluid outlet steam temperature is 327.7 ℃; when the molten salt pump is started, the outlet steam temperature is 362.2 ℃. The total pressure drop of the system and the maximum metal wall temperature under both operating conditions are within safe and reasonable ranges, and no flow instability occurs. This comprehensively evaluates the safety and reliability of the molten salt thermal storage heat exchanger during operation and provides a theoretical basis for the molten salt energy storage technology coupled with coal-fired power generation.关键词：molten salt heat storage heat exchanger;molten salt side heat transfer coefficient;flow distribution;pressure drop calculation32|50|0更新时间：2025-07-09
- 摘要：Given that the residual heat removal pump (RHRP), a core component of a nuclear power plant's residual heat removal system (RRA), operates under harsh gas-liquid two-phase conditions, the influence of gas content on its head and efficiency, as well as the underlying mechanisms are investigated. Based on the SST k-ω turbulence model and the Euler-Euler multiphase model, numerical simulations are conducted on an RHRP with splitter blades under varying gas volume fractions and bubble sizes. This study analyzes the velocity variations in the middle and rear sections of the impeller and the gas phase distribution inside the pump, exploring the impact of gas presence on RHRP performance and its mechanisms. The results indicate that gas content in the inflow conditions increases hydraulic losses: at gas volume fractions of 5% and 10%, the head decreases by approximately 9.2% and 20.0%, respectively, while efficiency drops by about 6.4% and 12.5%. Gas primarily accumulates on the pressure side of the blades, at the inlet of the splitter blades, and in the gaps between the impeller and guide vanes. The presence of gas causes a greater increase in relative velocity on the suction side than on the pressure side at the inlet of the splitter blades, leading to flow separation and vortex formation, which promote gas accumulation. Additionally, the absolute velocity at the impeller outlet changes—compared to gas-free conditions, the average absolute velocity decreases by 4.5% and 8.9% at 5% and 10% gas content, respectively. Moreover, the absolute velocity increases on the suction side and decreases on the pressure side, exacerbating flow non-uniformity at the outlet and hydraulic losses in the guide vanes. These findings provide technical guidance for the design of RHRPs with splitter blades under gas-liquid two-phase conditions and can be extended to other centrifugal pumps with splitter blades.关键词：residual heat removal pump;gas liquid two-phase system;splitter blades;head and efficiency27|26|0更新时间：2025-07-09
- 摘要：To address the common issues of large end-effector trajectory errors and the difficulty in meeting diverse transport requirements in industrial transfer robots, based on the ideas of hybrid and metamorphic mechanisms, a metamorphic hybrid robotic arm with two motion modes is designed. The stiffness characteristics of the wrist and shoulder spatial mechanisms are analyzed and optimized. Based on screw theory and the required degrees of freedom, a topological design of the wrist and shoulder mechanisms is completed, followed by mode switching through metamorphic design. Using the principle of stiffness superposition for parallel mechanisms, joint stiffness models for the wrist and shoulder mechanisms are established, and stiffness design objectives are proposed to compensate for errors. Topological dimensions are treated as design variables, and the stiffness models are matched with the stiffness design objectives to analyze the impact of design variables on stiffness characteristics, thereby determining the design direction for topological dimensions. Static simulations of the wrist and shoulder mechanisms are conducted using ANSYS software to obtain the maximum joint deformation of each mechanism. The simulation results indicate that, under a constant load, the maximum joint deformation of the wrist mechanism increases by 2.85% to 121.21% after adjusting the topological dimensions. In contrast, the maximum deformation of the shoulder mechanism decreases by 3.18% to 19.75% following changes in topological parameters. These simulation results verify that the design direction of topological dimensions is consistent with the stiffness design direction of the mechanisms. This study provides a reference for multi-objective optimization of mechanisms and error compensation methods.关键词：hybrid robot;spiral theory;metamorphic mechanism;joint stiffness model;error compensation;topological dimensions18|10|0更新时间：2025-07-09
- 摘要：This study aims to optimize the separator-electrolyte system by investigating the compatibility between ionic liquid-based electrolytes and commercial separators, thereby enhancing the performance of lithium metal batteries. Three commercial polypropylene separators (PP2500, PP3501, and PP2325) are selected and combined with a specific ionic liquid-based electrolyte (tributyl (methoxymethyl) phosphonium hexafluorophosphate, [P4441O1][PF6]) to construct different separator-electrolyte systems. The lithium-ion mobility, lithium deposition behavior, and lithium metal battery performance of these systems are systematically analyzed. The results show that the PP3501 separator exhibits the best compatibility with the ionic liquid-based electrolyte, achieving a high lithium-ion conductivity (0.103 mS/cm) and uniform lithium deposition on the lithium metal surface. This promotes stable cycling of Li|LiFePO4 batteries under high loading (LiFePO4 active material loading of 11.25 mg/cm2), with an initial discharge specific capacity of 129 mA·h/g at a rate of 0.5C (where C represents the battery charge/discharge rate). The findings provide theoretical and practical guidance for separator selection when using ionic liquids as electrolytes.关键词：ionic liquid-based electrolyte;lithium metal battery;lithium deposition behavior;separator-electrolyte system17|25|0更新时间：2025-07-09
- 摘要：To address the challenges of inaccurate state of charge (SOC) estimation and poor robustness in non-Gaussian noise environments, an extended Kalman filter algorithm based on the generalized mixed maximum correntropy criterion (GMMCC-EKF) is proposed. The algorithm employs a kernel function composed of two generalized Gaussian functions to derive the generalized mixed correntropy, inheriting the flexibility of generalized Gaussian kernels. Through statistical linearization techniques, both state errors and measurement errors are incorporated into a unified cost function, and the optimal estimation of nonlinear equations is obtained via fixed-point iteration. By integrating the generalized mixed maximum correntropy criterion with the extended Kalman filter, the algorithm enhances stability in non-Gaussian noise environments and improves accuracy in processing complex data. To validate the algorithm's effectiveness, two different types of lithium-ion batteries are tested under dynamic stress test (DST) conditions and new European driving cycle (NEDC) conditions at various ambient temperatures (10 ℃, 25 ℃, and 40 ℃). Experimental results demonstrate that at 25 ℃ under uniform mixed noise conditions, the GMMCC-EKF algorithm improves estimation accuracy by 90.1% and 83.9% compared to the conventional extended Kalman filter (EKF) and maximum correntropy criterion EKF (MCC-EKF), respectively, for No.1 battery 1. Similarly, for No.2 battery, accuracy improves by 72.4% and 47.4%. The algorithm also maintains superior performance at 10 ℃ and 40 ℃. Under Laplacian mixed noise conditions at 25 ℃, the GMMCC-EKF algorithm exhibits significant accuracy improvements for both No.1 battery and No.2 battery compared to the other two algorithms. Additionally, with erroneous initial values, the GMMCC-EKF algorithm rapidly converges to the true SOC. The proposed algorithm demonstrates high estimation accuracy, strong adaptability, and superior robust performance, providing an effective solution for SOC estimation in non-Gaussian noise environments.关键词：state of charge;generalized mixture maximum correlation-entropy criterion;extended Kalman filter;non-Gaussian noise22|13|0更新时间：2025-07-09
- 摘要：To effectively improve the thermal insulation performance of liquid hydrogen storage tanks, a transient heat and mass transfer model for vacuum multilayer insulated liquid hydrogen storage tanks is developed, and the effect of integrating a vapor-cooled shield with ortho-para hydrogen catalytic conversion is investigated. Dimensionless parameters, including the vapor consumption factor (ηc) and the dormancy period extension factor (ηd), are introduced to quantify vapor consumption and tank dormancy period, respectively. A unit factor (η), defined as the ratio of ηd to ηc, is used to characterize the heat-leak shielding capability of the vapor-cooled shield. A comparative analysis is conducted on the effects of key parameters, such as the dimensionless position of the vapor-cooled shield, mass flow rate, and activation timing, on the tank dormancy period, with and without ortho-para catalytic conversion. The results indicate that: Both ηd and η initially increase and then decrease as the dimensionless position of the vapor-cooled shield increases; when ηc=0.012 8 and the dimensionless position of the vapor-cooled shield is 0.167, the inclusion of ortho-para catalytic conversion yields the maximum improvement in both metrics (22.77%) compared to the non-catalytic case; as the mass flow rate of the vapor-cooled shield decreases, both metrics first increase and then decrease; the improvement in both metrics is more pronounced when the dimensionless position and mass flow rate of the vapor-cooled shield are relatively small; both metrics initially increase and then decrease with delayed activation of the vapor-cooled shield; under conditions where ηc=0.025 6 and the dimensionless position of the vapor-cooled shield is 0.233, activating the shield at 40.51 d achieves the maximum improvement of 22.32% in η with ortho-para catalytic conversion.关键词：liquid hydrogen tank;vacuum multi-layer insulation;vapor-cooled shield;hydrogen para-ortho catalytic conversion;transient heat and mass transfer model22|25|0更新时间：2025-07-09
- 摘要：To address the corrosion issues of nickel-based alloys in a hydrogen-containing supercritical water environment, this study explores the corrosion processes of Inconel 600 and Inconel 625 alloys through systematic experimentation, revealing their corrosion mechanisms. A systematic comparison is made of the corrosion processes of the two alloys under different temperatures (575, 600, and 625 ℃), different hydrogen partial pressures (1, 2, and 3 MPa), and different corrosion durations (72, 120, and 168 h). The corrosion mass gain patterns, surface elemental valence state distributions (XPS), and surface morphology characteristics (SEM) of the experimental samples are analyzed. The experimental results indicate that Inconel 625 alloy shows changes in mass after 120 h and 168 h of corrosion; both Inconel 600 and Inconel 625 alloys, due to their lower Fe/Ni ratio and approximately 20% Cr content, easily form dense Fe-Cr and Ni-Cr spinel oxide structures, which provide good protection against corrosion, thus exhibiting excellent hydrogen corrosion resistance; when a certain amount of Cr (20% by mass) is present, a higher Fe/Ni ratio facilitates the formation of stable FexCr(3－x)O4 and FemNi(3－m)O4, which exhibit better hydrogen embrittlement resistance; among the two materials, Inconel 625 has superior hydrogen corrosion resistance compared to Inconel 600. The findings provide support for material selection in containers used in hydrogen-containing supercritical water environments.关键词：hydrogen-containing environment;supercritical water;Ni-based alloy;corrosion mechanism33|30|0更新时间：2025-07-09
- 摘要：To improve the combustion efficiency of micron-sized aluminum powder and its catalytic performance for energetic molecules, iron single-atom catalysts (Fe1/Al) loaded on micron-sized aluminum powder are prepared using the chemical vapor transport (CVT) method in this study. The loading amount, structure, and physicochemical properties of the single-atom catalysts are characterized using inductively coupled plasma optical emission spectrometry (ICP-OES), aberration-corrected scanning transmission electron microscopy (AC-STEM), X-ray absorption fine structure spectroscopy (XAFS), and X-ray photoelectron spectroscopy (XPS). Thermogravimetric differential scanning calorimetry (TG-DSC) is used to compare the thermal reaction performance of the materials before and after modification by CVT method, and the catalytic decomposition performance of a series of materials on dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) is investigated. Results indicate that the iron species on the surface of the catalysts prepared by the CVT method exhibit a high degree of atomic-level dispersion. The CVT method allows for controlled preparation in terms of iron single-atom content and catalyst yield. The thermal reaction performance of the series of single-atom catalysts, as well as their catalytic decomposition performance on TKX-50, show significant improvements compared to unmodified aluminum powder. Among them, the Fe1/Al catalyst with a loading of 5.0% iron exhibits the best catalytic effect on TKX-50, with a peak temperature of the thermal catalytic decomposition reaction reduced by 19.3 ℃ and 39.1 ℃ compared to unmodified aluminum powder. This study achieves the controlled preparation of single-atom combustion catalysts loaded on aluminum powder, providing a new method and approach for the modification of micron-sized aluminum powder.关键词：micron-sized aluminum powder;single-atom catalysts;chemical vapor transfer;controllable preparation;TKX-5030|12|0更新时间：2025-07-09
- 摘要：To address the issues of empiricism, accuracy loss, and repeated calculation of interface heights caused by the piecewise approximation strategy in interface reconstruction and the volume of fluid equation solving using the circle-based interface reconstruction (CIR) algorithm, an integration circle-based interface reconstruction (ICIR) algorithm is proposed. This algorithm employs a series of processing strategies to achieve volume fraction solutions based on integration, effectively avoiding empirical interface segmentation and repeated solving of interface heights in each segment. Test results indicate that in a static test involving the random reconstruction of 1 000 circular interfaces, the ICIR algorithm improves reconstruction accuracy by 7.71% compared to the CIR algorithm, with an acceleration ratio of 6.78 for solving the interface equation. In the horizontal motion test of a simple vapor bubble and the complex time-reversed single-vortex test, the ICIR algorithm enhances accuracy by 3.96% and 13.09%, respectively, while computational efficiency improves by 40.88% and 68.31%. Overall, the ICIR algorithm significantly boosts computational efficiency and enhances the accuracy of interface reconstruction.关键词：interface reconstruction;curved interface reconstruction;gas-liquid two-phase flow21|21|0更新时间：2025-07-09
- 摘要：To address the deterioration of low-frequency torsional vibration performance during the transient mode-switching process in power-split hybrid electric vehicle transmission systems, a hierarchical dynamic coordinated control strategy based on finite-time prescribed performance control with control barrier functions (FTPPC-CBFs) is proposed. For this series-parallel hybrid configuration, the lever method is adopted to establish a low-frequency torsional vibration dynamic model for different mode-switching stages. In the upper-layer design, the clutch speed synchronization stage is selected as the primary research phase. Based on the design principles of general prescribed performance control (PPC), a prescribed performance function is constructed using mode-switching performance metrics. Control Barrier Functions (CBFs) are introduced to transform the prescribed performance constraint problem into a quadratic programming problem, forming the Prescribed Performance Control with Control Barrier Functions (PPC-CBFs) strategy. In the lower layer, finite-time adaptive power integration (FTAAPI) is employed to achieve rapid error convergence control. The combination of the upper-layer PPC-CBFs and the lower-layer FTAAPI constitutes the FTPPC-CBFs control strategy, which is validated through hardware-in-the-loop (HIL) testing. Results show that, compared to FTAAPI control, sliding mode control (SMC) under ordinary PPC, and FTAAPI-PPC control, the FTPPC-CBFs strategy reduces the impact severity by 50.12%, 37.42%, and 42.92%, respectively. Under sudden disturbance conditions, the jerk with CBFs constraints is 9.99 m/s3, whereas without CBFs, it reaches 13.76 m/s3-exceeding the prescribed jerk standard. HIL test results demonstrate that, compared to the other three control strategies, FTPPC-CBFs reduces jerk by 81.89%, 77.30%, and 43.01%, respectively. Under sudden disturbances, the jerk is maintained at 9.71 m/s3, confirming consistency between experimental and simulation conclusions.关键词：hybrid electric vehicle;torsional vibration;control barrier function;hardware in the loop25|16|0更新时间：2025-07-09
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0