最新刊期
卷 58 ， 期 3 ， 2024
- 摘要：With the proposal of the “carbon peaking and carbon neutrality” target, the scroll expander has garnered attention as a mechanical device for the recovery of low-grade energy. An overview of the theoretical research achievements of scroll expanders in recent years are provided, mainly including profile theory, thermodynamics, and computational fluid dynamics(CFD)simulation. Subsequently, the application of scroll expanders in organic Rankine cycles(ORC)is summarized. The application research results of scroll expanders in transcritical CO2 refrigeration cycles are collated. Lastly, the future research directions for scroll expanders are projected. The findings indicate that the variable wall thickness scroll expander, which can increase the volumetric ratio without lengthening the leakage path, will become the main direction for future profile optimization; CFD simulation has emerged as a significant research tool; lubricant is a key factor affecting the performance of scroll expanders, where increasing the viscosity of the lubricant can enhance efficiency, while an excess of lubricant will reduce the performance; working pressure is the most critical factor affecting the performance of scroll expanders, with phenomena such as over-expansion, under-expansion, and leakage leading to decreased performance. Moreover, the integrated scroll compression-expansion unit, which combines the expander and compressor into one casing, significantly simplifies the system structure and improves energy recovery efficiency, proving to be an effective way to enhance the performance of CO2 heat pump air-conditioning systems for new energy vehicles. Based on current research achievements and industry demands, future development of scroll expanders should continue to delve into and optimize profile design, reduce leakage, and optimize working pressure, to meet the growing needs for energy recovery and environmental protection.关键词：scroll expander;carbon peaking and carbon neutrality target;organic Rankine cycles;scroll compressor-expander unit305|39|0更新时间：2025-07-09
- 摘要：Capturing the transient evolution of soot under diesel-like conditions through experimental methods is challenging. The transient formation characteristics and kinetic of soot in-flame of n-dodecane spray under high-temperature and high-pressure conditions is investigated in present study. Experimentally, the combined extinction and radiation(CER)methodology and combustion image velocimetry(CIV)are applied to capture the transient distributions of soot volume fraction, soot temperature, and soot velocity field of n-dodecane spray flames from a single-hole injector under high-temperature and high-pressure conditions. Numerically, a coupled model combining the Eulerian spray model and unsteady flame progress variable combustion model is developed in the OpenFOAM environment. The numerical results of the spray combustion process exhibit a high level of agreement with experimental data. The results show that, compared to the reference condition, in the lower injection pressure condition, the shorter lift-off length(LOL)and the longer soot residence time within the interval equivalence ratio Φ>2 significantly propel the formation of soot, leading to an 80% increase in peak soot mass. In the higher-temperature condition, there is no significant difference in the soot residence time within the interval Φ>2, while the shorter LOL leads the fuel to ignite at higher equivalence ratios, resulting in a significant increase in soot formation, with an 88% increase in peak soot mass. In the oxygen-rich condition, the flame temperature is the highest, which increase the particle velocity of soot. Consequently, the residence time of soot within the interval Φ>2 is significantly reduced. Additionally, owing to the lower equivalence ratio in the flame, peak soot mass is reduced by 42%.关键词：n-dodecane;combined extinction and radiation imaging technique;Eulerian spray model;soot formation characteristics71|25|0更新时间：2025-07-09
- 摘要：To enhance the aerodynamic efficiency of high-load turbine stages, a spline surface-based non-axisymmetric endwall profiling method is developed. Based on this parametric profiling method, combined with efficient intelligent optimization algorithms and validated numerical simulation techniques, an optimization framework for designing non-axisymmetric endwalls in turbines is established. Taking a high-pressure turbine stage with a low aspect ratio as the study object, with efficiency as the optimization objective and the mass flow rate as a constraint condition, the non-axisymmetric endwall optimization design is conducted under the stage environment and engine operating conditions. The results show that compared with the reference design, the total efficiency of the turbine stage is increased by 0.26% after the optimization design. The non-axisymmetric endwall changes the pressure distribution near the lower endwall of the rotor blade, and the pressure coefficient at the suction side of the rotor blade is significantly improved compared with the reference design. This reduces the lateral pressure gradient in the blade passage and suppresses the secondary flow in the passage. The non-axisymmetric endwall changes the vortex system structure in the blade passage. Compared to the reference design, the non-axisymmetric endwall causes the horseshoe vortex's pressure side leg to migrate along the pressure side in the blade passage before merging into the passage vortex near the passage outlet. This lowers the intensity of the passage vortex, which then reduces aerodynamic losses and improves turbine stage efficiency.关键词：high pressure turbine;non-axisymmetric endwall;aerodynamic performance;optimization design119|9|0更新时间：2025-07-09
- 摘要：To achieve the hourly optimization of the mechanical vapor recompression(MVR)system under the condition of fluctuating feed flow and concentration in industrial wastewater treatment processes, an hourly optimization model based on the adaptive SPAE2 algorithm is proposed in this study. The SPEA2 algorithm is employed along with adaptive crossover probability, mutation probability, and a combination weighting method for multi-objective hourly optimization. The total power consumption and total heat transfer area of the system are considered as optimization objectives to obtain the optimal combination of evaporation temperature and compression temperature rise. Building on the original research, the SPEA2 algorithm is improved, and the original data is compared with the optimization results. It is concluded that the adaptive SPEA2 algorithm exhibits stronger global optimization ability, leading to more accurate optimization results. The least squares method is used to fit the optimization results. When compared with the results under constant evaporation conditions, the optimization results show the following improvements on average: the total power consumption decreases by 123.7 kW, the heat transfer area decreases by 36.3 m2, the coefficient of performance(COP)and energy efficiency increase by 8.8% and 26.6%, and the energy loss decreases by 102.3 kW. These results indicate that the hourly optimization model established for the system can obtain the hourly variations of equipment parameters under fluctuating feed conditions. This improves the system's energy utilization efficiency and thermodynamic performance.关键词：mechanical vapor recompression;hourly optimization;adaptive genetic algorithm;wastewater;performance analysis58|6|0更新时间：2025-07-09
- 摘要：To evaluate the leakage performance of the novel liquid hole-pattern stator/parallel-grooved rotor seal under rotor eccentricity and improve its operational stability, a central composite design(CCD)is proposed as a design of experiments(DOE)method. A sensibility analysis of key geometric parameters, including cavity depth, cavity length, hole depth, and hole diameter, is conducted to investigate their impact on the leakage performance and rotor stability. A numerical computation approach is adopted, utilizing the mesh deformation technique and steady-state RANS equations, to solve for the leakage, static aero-excitation force, and static stiffness coefficient of the novel liquid seal for 25 combinations of geometric parameters. The computations are performed under two eccentricity values(0.1 and 0.2). The main effects plot is obtained, taking the leakage, static aero-excitation force, and static stiffness coefficient as responses and the four geometric parameters as variables. The results indicate that eccentricity has little effect on the leakage and its parameter sensitivity, and the leakage is the smallest when cavity depth, cavity length, hole depth, and hole diameter are at 40%, 24%, 56%, and 44% of their respective levels. When the rotor is eccentric, the tangential force decreases monotonically with the increase of cavity depth and width, while it increases first and then decreases with the increase of hole depth and diameter. The radial force increases monotonically with the increase of cavity depth, while it decreases first and then increases with the increase of cavity width. When eccentricity increases to 0.2, a geometric parameter combination can be identified that maximizes the static direct stiffness. In this case, the cavity depth, cavity width, hole depth, and hole diameter are at 24%, 48%, 40%, and 64% of their respective levels. Under both eccentric and non-eccentric rotor conditions, the static cross-coupling stiffness decreases monotonically with the increase of cavity depth and width. When the rotor is eccentric, the static cross-coupling stiffness increases first and then decreases with the increase of hole depth and diameter. This study can provide reference for the performance analysis and structure design of the liquid hole-pattern stator/parallel-grooved rotor seal.关键词：liquid seal;leakage flow rate;static fluid-induced forces;static stiffness coefficients;design of experiments method59|25|0更新时间：2025-07-09
- 摘要：To evaluate the influence of hydrogen-blended natural gas on dry gas seal(DGS)at the shaft end of pipeline compressor, a numerical prediction model of DGS performance considering choked flow effect is proposed, as well as the static characteristics and the startup characteristics under different hydrogen-blended ratios are analyzed. Firstly, the reliability of the numerical model is verified by the experimental data of gas film pressure distribution and opening force of air medium spiral groove DGS. Then, aiming at the spiral groove DGS of GE PCL800 natural gas pipeline compressor, the effects of four hydrogen-blended ratios(volume fraction of H2 of 0, 10%, 20% and 30%, respectively)and five inlet pressures(4, 6, 8, 10 and 12 MPa)on the static characteristics are analyzed. Finally, the effects of rotational speed, inlet pressure, balance ratio and spring specific pressure on the startup characteristics are discussed. The results show that the prediction model can predict effectively the influence of choked flow on seal performance under high pressure difference. The hydrogen-blended ratio has little influence on the static characteristics, such as opening force, leakage and gas film stiffness. The critical opening speed(the opening critical speed increases 8.51%—16.90% when the hydrogen blended ratio increases 30%)of DGS increases with the increase of hydrogen-blended ratios and the opening difficulty increases after hydrogen-blending. In addition, choosing appropriate balance ratio and spring specific pressure is beneficial to the smooth opening of DGS. The research work can provide theoretical reference for the efficient design and reliable operation of DGS at the shaft end of natural gas pipeline compressor after hydrogen-blending.关键词：dry gas seal;hydrogen-blended natural gas;choked flow effect;startup characteristics63|6|0更新时间：2025-07-09
- 摘要：Existing methods for measuring the centroid trajectory of bearing cages often require structural modifications to the bearing, which can distort the assessment of its dynamic characteristics. In contrast, image-based methods offer a non-invasive alternative but they depend on marker precision and tracking accuracy. This can make it challenging to obtain an accurate centroid motion representation. This paper proposes a method for extracting motion trajectories for rolling bearing cages using an image processing program with a subpixel edge detection algorithm. This method accurately identifies and extracts the cage centroid's trajectories without altering the bearing's structure. Experiments are conducted on bearing cages with different guidance modes. The results show that the cage's motion trajectory is influenced by the structures of the cage as well as the inner and outer rings of the bearing, resulting in varying shapes of the trajectory. Within the range of experimental speeds, the stability of cage motion improves with the increase of rotational speed. These results confirm the effectiveness of the proposed trajectory extraction method. This paper presents a convenient and accurate testing method for investigating the dynamic characteristics of bearing cages, allowing for the effective extraction of the centroid trajectory of bearing cages.关键词：rolling bearing;cage trajectory;image processing;bearing dynamic characterization91|16|0更新时间：2025-07-09
- 摘要：To address the issue that wind turbines’ supervisory control and data acquisition(SCADA)system contains a significant amount of data about abnormal records, which affects the accurate representation of the turbines’ operational status, a method for identifying abnormal data based on density-based spatial clustering of applications with noise(DBSCAN)is proposed. which affects the accurate representation of the turbines’ operational status, a method for identifying abnormal data based on density-based spatial clustering of applications with noise（DBSCAN）is proposed. Based on the characteristics of the wind speed-power scatter curve, this method involves the use to selec-t the key clustering parameters： of prediction errors and classification accuracy neighborhood radius and minimum number of sample points in the neighborhood. It avoids the subjectivity of manually determining the clustering parameters, allowing for a fully automated parameter selection process. As a result, it achieves effective identification of abnormal data in a wind turbine’s SCADA system. The proposed method is validated using monitoring data from wind turbines in a specific wind farm. The results demonstrate that the method helps to retain as much normal data as possible while ensuring the removal of abnormal data. It also shows superior anomaly identification performance compared to k-distance graph and KANN-DBSCAN, an improved algorithm based on k-nearest neighbors. This study provides valuable insights for the status analysis of wind turbines.关键词：wind turbine;abnormal detection;spatial clustering;wind speed-power curve62|17|0更新时间：2025-07-09
- 摘要：To address the issue that traditional spectral amplitude modulation methods are susceptible to noise, this paper proposes a parameterized S spectral amplitude modulation method, where a parameterized S-transform is applied to obtain the amplitude of a signal in the time-frequency domain. First, the parameterized S-transform is used to convert the signal into the time-frequency domain and obtain its amplitude and phase information. Then, different weights are assigned to the amplitude in the time-frequency domain to alter the contribution of different energy frequency components in the signal. Lastly, the modulated amplitude is combined with the original phase, and the parameterized inverse S-transform is used to reconstruct a series of modified signals for computing squared envelope spectra and extracting fault characteristics. The simulation and experimental results indicate that the amplitude information obtained using the proposed method is more accurate and comprehensive compared to traditional spectral amplitude modulation methods. This method exhibits greater robustness in high-noise environments, and can effectively diagnose faults in the outer and inner rings of rolling bearings and compound faults. The proposed method is compared with traditional spectral amplitude modulation methods and fast Kurtogram. The results demonstrate that the parameterized S spectral amplitude modulation can not only detect bearing fault information in high-noise environments, but also extract multiple fault components simultaneously. Therefore, it exhibits obvious advantages in the diagnosis of rolling bearing faults.关键词：rolling bearing;fault diagnosis;spectral amplitude modulation;parameterized S spectral amplitude modulation245|10|0更新时间：2025-07-09
- 摘要：To address the limitations of existing tensor decomposition-based methods for compressing convolutional kernels, such as the trade-off between spatial and temporal lightweight and excessive reliance on convolutional bottleneck structure, a compression method with layered matrices called KCPStack is proposed in this paper which offers considerable compression and acceleration capabilities. Firstly, from the perspective of matrix multiplication, the convolutional kernels are split by channel and subjected to a second-order Khatri-Rao Product(KCP)decomposition and the resulting factor tensors are combined into two-layer weight matrices, thereby transforming the convolutional computation into a two-layer lightweight convolutional structure with higher inference efficiency. Secondly, a comparison is made between the space complexity regarding parameter reduction and time complexity regarding inference computation of the KCPStack method and other typical tensor decomposition-based compression methods for convolutional kernels. Lastly, the KCPStack method is deployed on the RK3588 neural processing unit to develop related applications to meet the object detection and recognition needs for the real scene. The experimental results demonstrate that, compared with existing tensor decomposition-based methods, the proposed KCPStack method achieves the highest inference computation efficiency under the same tensor rank or comparable parameter quantity conditions. On the benchmark datasets CIFAR-10 and ImageNet for image classification, the KCPStack method controls the accuracy loss to around 1% while achieving a maximum parameter reduction of 85.0% and a computational saving of 79.8%. On the benchmark dataset COCO for object detection and recognition, the KCPStack method exhibits an average precision drop of less than 1% compared to the baseline model. When the KCPStack method is adopted for an object detection and recognition task in the real scene, an average precision of 95.4% and of an image processing frame rate of 35 frames per second are achieved on the RK3588 neural processing unit, and it requires only 33.1 MB of memory consumption.关键词：KCP tensor decomposition;convolutional kernel compression;inference efficiency;layered matrices;object detection and recognition31|7|0更新时间：2025-07-09
- 摘要：To investigate the mechanism of humans' adapting to the load fore-aft dynamic interference during walking and design a reliable wearable assistive robot strategy, a human-load coupling system is modeled as a two-degree-of freedom forced vibration system in this study. Firstly, based on the principles of mechanical vibration, the characteristics of the human-load coupling system is analyzed to examine the influence of different walking frequencies on human and load displacement. A hypothesis is proposed that humans adapt to the influence of load fore-aft disturbance by adjusting their walking frequency. Then, an experimental platform of load fore-aft dynamic disturbance is built to examine the muscle synergy characteristics and leg excitation frequencies of subjects walking without any added load and under load fore-aft disturbance. Compared with simulation results, the experimental results show that human walking under load fore-aft disturbance is a process of adaptive adjustment that eventually reaches dynamic stability. Specifically, under loaded conditions, the amplitude of upper limb and trunk swing is amplified by more than 60% compared to unloaded conditions. The influence of load fore-aft dynamic disturbance on upper limb and trunk swing is reduced by adjusting the walking frequency and muscle synergies. Under loaded conditions, the walking frequencies at different walking speeds tend to converge towards the natural frequency of the human-load coupling system. When the walking frequency is set to be equal to the natural frequency, the leg excitation frequency increases by 4.30% during slow walking and decreases by 2.71% during fast walking when reaching a steady state. The walking control strategy is changed compared to unloaded conditions to adapt to the influence of load fore-aft disturbance.关键词：load traverse;adaptive adjustment;human-weight-bearing coupling;walking with weights25|30|0更新时间：2025-07-09
- 摘要：To address the problem of unsatisfactory user experience quality caused by the fluctuation of ground device quantity in an air-ground network, a solution for intelligent network resource allocation and dynamic deployment of base stations with multiple unmanned aerial vehicles(UAVs)is proposed. Firstly, considering user experience quality and the energy constraints of UAVs and ground devices, the problem is modeled with the objective of minimizing the total system energy consumption. Secondly, the dynamic deployment of multiple UAVs is transformed into a Markov decision process(MDP)with a continuous action set, and a reward function based on energy penalty is designed according to the optimization objective. Thirdly, a deep reinforcement learning algorithm based on deep deterministic policy gradient(DDPG)is used to solve this problem. Lastly, the effectiveness and superiority of the proposed solution are verified through simulation and comparative experiment. Experimental results show that, for scenarios with a massive number of users, the proposed algorithm exhibits better convergence and higher cumulative rewards compared to deep reinforcement learning and actor-critic algorithms. In comparison to single UAV and traditional ground base station deployment solutions, the proposed solution reduces energy consumption by approximately 30% to 40%, and improves user satisfaction with service quality by around 50% to 60%.关键词：unmanned aerial vehicle;resource allocation;dynamic deployment;reinforcement learning algorithm48|21|0更新时间：2025-07-09
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Research on an Imaging Acceleration Method for Embedded Systems of Electrical Capacitance Tomography
摘要：To increase the image reconstruction speed of electrical capacitance tomography(ECT)in embedded system design, this paper proposes an acceleration method for image reconstruction algorithm in the context of the ARM+FPGA hardware architecture. The structure of the widely-used and robust iterative Landweber algorithm(ILA)is analyzed and then the loop structure within the ILA is modified taking advantage of the FPGA's pipeline features to achieve acceleration. Furthermore, according to the characteristics of the ARM+FPGA architecture, the task allocation of ARM and FPGA cores is discussed to further optimize the speed of the algorithm. To validate the effectiveness of the proposed algorithm, image reconstruction experiments are conducted on both a desktop computer(using MATLAB programming)and the ZYNQ platform(using the acceleration method proposed in this paper). The effectiveness of the proposed method is demonstrated using three parameters: image reconstruction time, relative error of the reconstructed image, and image correlation coefficient. The experimental results show that when using the platform built in this paper for imaging with ILA, the runtime for each image is reduced by 30%—40% compared with the time when using MATLAB programming on a PC. This study effectively increases the speed of iterative algorithm while maintaining reconstruction accuracy, demonstrating its applicability to hardware acceleration of ECT systems.关键词：electrical capacitance tomography;image reconstruction algorithm;hardware acceleration;embedded system42|13|0更新时间：2025-07-09 - 摘要：In this study, a combination of wet recovery process and supercritical hydrothermal synthesis technology is employed to produce high-value nano-zinc oxide products from zinc ash, and an economic analysis of this approach to zinc ash recycling is conducted. A sound system is established using Aspen Plus, and material costs and energy consumption during system operation are analyzed. The leaching rate of zinc in the zinc ash exceeds 95%, under the conditions of sulfuric acid concentration of 2 mol·L-1, solid-liquid ratio of 1:8, leaching temperature of 50 ℃, leaching time of 2 h, and stirrer speed of 300 r·min-1. Fe, Al, Ni, Cu and other impurities are eliminated in the impurity removal process, and the zinc content in the solution after impurity removal reaches 97%. The leaching solution of zinc ash is used to synthesize nano-zinc oxide with an average particle size of 26 nm under supercritical conditions of 400 ℃ and 25 MPa. The resulting zinc oxide exhibits excellent crystallinity and high purity. The comparison with nano-zinc oxide synthesized from pure materials validates the feasibility of this technology, which significantly improves the system's economic viability.关键词：recycling of zinc ash;supercritical hydrothermal synthesis;nano-zinc oxide;high-value utilization38|26|0更新时间：2025-07-09
- 摘要：To address issues like large chattering and slow response in traditional sliding mode control of permanent magnet synchronous motors(PMSMs), a new type of reaching law is designed. This approach incorporates a conventional exponential reaching law with an adaptable proportionality coefficient, system state variables, and the power term of the sliding mode surface to mitigate chattering while enhancing convergence speed. To avoid introducing differential terms of speed error and reduce high-frequency chattering in the system, an integral sliding mode surface is used to design an improved PMSM speed controller. To address the issue of reduced control accuracy and increased chattering in the control system caused by load disturbance fluctuations, a novel saturation function-based extended state observer(ESO)is devised. This ESO is utilized to estimate the load disturbance and the estimated disturbance value is fed forward to the improved sliding mode controller to further enhance the system's disturbance rejection capability. The numerical simulation results demonstrate that the proposed control strategy substantially improves the dynamic performance and disturbance rejection of the motor. When the motor is affected by load torque fluctuations, compared to PI control, the proposed control strategy reduces overshoot by about 23.1% and increases response speed by 62.5%. Compared to traditional sliding mode control, the proposed control strategy reduces overshoot by about 15.3% and increases response speed by 50%. The new sliding mode reaching law can effectively reduce sliding mode chattering. Compared to traditional sliding mode controllers, the improved sliding mode controller reduces motor chattering by about 50%.关键词：permanent magnet synchronous motor;sliding mode control;new reaching law;extended state observer;disturbance rejection feedforward compensation85|26|0更新时间：2025-07-09
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