最新刊期
卷 57 ， 期 9 ， 2023
- 摘要：In order to make full use of renewable energy and improve the efficiency of the power generation system, an integrated system based on solid oxide electrolytic water hydrogen production and energy storage and Allam cycle power generation was proposed. Specifically, the high-efficiency Allam cycle was applied to the energy storage system of electrolytic water hydrogen production and the energy storage system of hydrolysis was responsible for providing fuel and pure oxygen for the Allam cycle. Meanwhile, the thermodynamic calculation model of the system was established and the simulation calculation of the system was carried out through Matlab self-programming with a focus on analyzing the influences of turbine inlet and outlet parameters, isentropical efficiency of power equipment, electrolytic efficiency and minimum cycle temperature on the energy storage-generation system. The results show that the efficiency of the integrated system reaches 54.47% and the energy storage density is 214.85 kW·h·m-3 under the design condition; there are optimal turbine inlet temperature, optimal turbine inlet pressure and optimal turbine outlet pressure to make the system efficiency reach the peak; compared with other power equipment, the internal efficiency of the turbine has the greatest influence on the system performance, with the internal efficiency of the turbine increasing from 82% to 92% and the system efficiency seeing an improvement of 2.55 percentage points; the system performance can be improved by reducing the minimum cycle temperature. When the minimum cycle temperature is reduced from 26 ℃ to -4 ℃, the system efficiency is improved by 6.03 percentage points. This study can serve as a valuable reference for the development of new large-scale electric energy storage technology, and the results of parameter analysis can provide theoretical support for practical engineering applications.关键词：electrolytic water;Allam cycle;integrated system;thermodynamic analysis172|8|0更新时间：2025-07-09
- 摘要：In order to improve the film cooling effectiveness and reduce the aerodynamic loss of the gas turbine blade tips, an experiment was conducted to investigate the film cooling characteristics of the multi-cavity tips with inclined film holes, and the aerodynamic performance of these tips was numerically simulated. Firstly, the variation rule of the film cooling performance of four types of multi-cavity tips, of which the cavity number was one, two, three and four respectively, was measured under four blowing ratios(0.5, 1.0, 1.5 and 2.0)by the pressure sensitive paint technique. Secondly, after the validation of turbulence models, the SST k-ω turbulence model, which showed the most excellent agreement with experimental results, was adopted to simulate the flow field structure and aerodynamic loss of the multi-cavity tips. The results show that the multi-cavity tips have better film cooling coverage on the front and middle parts of the tips as well as the rims; the installed ribs of the multi-cavity tips can prevent the coolant from flowing downstream and induce vortices behind the ribs to involve the coolant, leading to better film cooling effectiveness on the upstream and downstream parts of the ribs; compared with the conventional cavity tips, the aerodynamic loss of the multi-cavity tips are lower, of which the three-cavity tips performs the lowest loss coefficient and it is 9.3% lower than that of the conventional cavity tip at most.关键词：gas turbine;multi-cavity tip;film cooling;pressure sensitive paint;aerodynamic characteristics103|40|0更新时间：2025-07-09
- 摘要：In order to solve the hot issue of the boundary layer flow separation in the design of bio-inspired aircraft at low Reynolds number, a method of unsteady flow control using flexible flaps on the lower surface of the airfoil was proposed in the paper based on the flow control mechanism of bird secondary feathers. Specifically, a general IB-LB-FEM fluid-structure coupling method with the immersed boundary method as the core was established, the effect of the position and stiffness coefficient of the flexible flap on the unsteady flow of NACA0012 airfoil was systematically studied, and the deformation law and unsteady flow control mechanism of the flexible flap under fluid-structure coupling were revealed. The results show that the influence of the flap near the trailing edge of the airfoil on the aerodynamics of the airfoil is more obvious with the maximum average lift-drag ratio being 33.32% higher than that of the airfoil without flaps; the flexible flap on the lower surface does not directly participate in the control of the flow separation on the surface of the airfoil, but it can form a new flow separation behind the flap by disturbing the unsteady flow on the lower surface of the airfoil, thus affecting the aerodynamics of the airfoil; by changing the stiffness coefficient of the flexible flap on the lower surface of the airfoil, the fluid-structure coupling characteristics of the flexible flap can also effectively improve the aerodynamics of the airfoil. Focusing on studying the flow control mechanism of the flexible flap, the study can provide a new research idea for solving the flow separation of bionic aircraft.关键词：flexible flap;immersed boundary method;flow control;fluid-structure coupling;unsteady flow44|24|0更新时间：2025-07-09
- 摘要：In order to investigate in depth the two-phase condensation flow during low-temperature gas expansion at supersonic speeds, a unified numerical model was developed using the Euler-Euler two-fluid model. Specifically, the phase transition model adopted the classical nucleation theory considering non isothermal effects and the Gyarmathy droplet growth theory which is capable of predicting both homogeneous and heterogeneous condensation of nitrogen gas. The numerical simulation of cryogenic nitrogen gas expansion and condensation in a Laval nozzle was carried out using Ansys Fluent, and the effects of different inlet temperatures and heterogeneous core parameters on the condensation behavior were analyzed. The simulation results show that with decreasing inlet temperature, the location of condensation gradually shifts towards the throat, and the liquid mass fraction and droplet size at the exit also increase; compared with homogeneous nucleation, the presence of heterogeneous cores reduces the free energy barrier of nucleation, allowing nitrogen to condense at relatively low degrees of supercooling; when the radius of the heterogeneous core is within a certain range, as the number of heterogeneous cores increases, heterogeneous condensation gradually becomes the dominant process in the growth of the liquid mass fraction until complete heterogeneous nucleation is achieved.关键词：cryogenic nitrogen;supersonic expansion;homogeneous nucleation;heterogeneous nucleation40|6|0更新时间：2025-07-09
- 摘要：In order to investigate the thermal stratification and boiling bubble features in the cryogenic propellant tank under great heat flux conditions, a visual platform was built, using liquid nitrogen as the test fluid. By adjusting the blowing temperature and speed, a heat flux boundary range of 1—16 kW·m-2 was achieved, which was basically consistent with the aerodynamic heat flow impact during rocket launching. The results show that a high heat flux at the tank wall surface does not necessarily bring about boiling bubbles; when the heat flux density is less than 2 kW·m-2, bubbles are generated in the near-wall region until the subcooling degree of the bulk liquid decreases to 1 K; comparatively, when the heat flux density exceeds 16 kW·m-2, a high subcooling degree of 10 K of the bulk liquid could yield boiling bubbles. When there is a large degree of subcooling in the bulk liquid, the aerodynamic heating during rocket launch only causes bubbles in the near-wall region. Increasing the pressurized gas injection rate during the pressurization period of the cryogenic tank could postpone the liquid temperature rise as well as boiling occurrence in the near-wall region. In addition, an empirical model was established to describe the boundary of boiling bubbles, which can offer preliminary predictions on whether propellant boiling occurs in bare-wall storage tanks under high heat flux, thus providing support for the design of the insulation scheme for the rocket tank.关键词：cryogenic propellant;boiling bubbles;two-phase flow behaviors;visualization test45|5|0更新时间：2025-07-09
- 摘要：In order to achieve higher thermal efficiency and lower emissions of methanol/diesel dual-fuel engines, an independent dual-direct injection system was built on a single-cylinder diesel engine and the operating range of the methanol/diesel dual-direct injection engine was conducted experimentally. Results show that the indicated thermal efficiency decreases with the increase of the methanol energy substitution ratio under low engine loads. But the increase of the methanol energy substitution ratio benefits the improvement of indicated thermal efficiency under medium and high engine loads. The highest indicated thermal efficiency of 43.4% could be achieved at an engine load rate of 79.5% and a methanol energy substitution ratio of 52.4%. Meanwhile, with the increase of the methanol energy substitution ratio, NOx and soot emissions decrease, but the opposite trends of HC and CO emissions are observed. Besides, the maximum methanol energy substitution ratio and its influence on the thermal efficiency of the engine were investigated under the full engine load and it was found that the maximum methanol energy substitution ratio of the dual-direct injection engine could reach up to 96.0% and the indicated thermal efficiency first increases and then decreases with the increase of the methanol energy substitution ratio and reaches a peak when the ratio increases to 50.0%. The research can provide experimental and data support for further optimization of the performance and emission characteristics of methanol/diesel dual-direct injection engines.关键词：methanol/diesel dual-fuel;dual-direct injection engine;methanol energy substitution ratio;operating range;thermal efficiency;emissions characteristics62|21|0更新时间：2025-07-09
- 摘要：In order to monitor the working state of the diesel particulate filter(DPF)in real time, it is necessary to establish the corresponding fault diagnosis strategy. First, a DPF soot capture model was established by using GT-POWER software, and the penetration of DPF was calibrated through engine emission tests. Then, different degrees of blockage faults and breakage faults of DPF were simulated and pressure drop and capture efficiency were selected for research to analyze their sensitivity to fault degree. Finally, the pressure drop and sensor signal boundary of the faulty parts under world harmonized transient conditions were studied by building test benches and making broken and blocked parts that met the legal limits and a fault diagnosis method of coupling the differential pressure sensor and the particle sensor was proposed. Research shows that the DPF pressure drop increases exponentially with the increase of blockage degree, while the increase of capture efficiency is relatively gentle. However, the DPF pressure drop and capture efficiency gradually decrease with the increase of the breakage degree. Under the condition of high speed, the capture efficiency decreases to 50% when the breakage degree reaches 20%, and when the breakage degree increases to 50%, the DPF completely fails regardless of working condition. In addition, the breakage fault test determines that the lower limit of the pressure drop boundary of the DPF breakage fault is 0.1 kPa and the upper limit of the sensor signal boundary is 10 nA; the blockage test determines that the upper limit of the pressure drop boundary of the DPF blockage fault with a carbon load of 7 g/L is 1.75 kPa, and the lower limit of the sensor signal boundary is 15 nA.关键词：diesel particulate filter;leakage current particle sensor;pressure drop;capture efficiency;fault diagnosis54|5|0更新时间：2025-07-09
- 摘要：The modeling and solving process of the double row tapered roller bearing is complex. To solve the problem, a quasi-static model of double row tapered roller bearings was established in the paper based on the slice method, and the solution of the model was realized by combining the homotopy algorithm and the Newton algorithm, which overcame the problem of the high dependence of the traditional nonlinear iterative algorithm on the initial value to a certain extent, and the stiffness characteristics of double row tapered roller bearings under different working conditions were analyzed. The calculation results show that the stiffness characteristics of double row tapered roller bearings are affected by bearing speed and preload displacement. Under the condition of only preload, the radial and axial stiffness of bearings decreases with the speed increasing from 0 r/min to 4 000 r/min, and increases with the preload displacement increasing from 0.005 mm to 0.015 mm. When the axial force increases from 10 kN to 14 kN, their radial and axial stiffness decreases, and when the axial force increases from 14 kN to 19 kN, their radial and axial stiffness increases, and the turning point is the separation point between the second row of rollers and the inner raceway. When the rotation speed increases, the axial force required to produce the separation point decreases, and when the preload displacement increases, the axial force required to produce the separation point increases.关键词：double row tapered roller bearings;stiffness characteristics;quasi-statics model;homotopy-Newton method48|8|0更新时间：2025-07-09
- 摘要：In order to fully explore the optimized load-bearing structure of the tunnel boring machine cutterhead, the variation and reconstruction mechanism for the dynamic load-bearing structure based on the classical layout scheme was further researched. Specifically, the explicit topology optimization method was used as a design tool to drive the variation and reconstruction of the load-bearing structure of the tunnel boring machine cutterhead and the EFEM was also used to achieve the suppression of the structural dynamic response by guiding and enhancing the dissipation of the vibration energy of the tunnel boring machine cutterhead. In this paper, the cutterhead structure of a certain type of the EPB tunnel boring machine was verified. The verification results show that under the same opening rate and load input conditions, compared with the original cutterhead structure, the average deformation of the cutterhead structure designed in the paper is reduced by 24.49%, the maximum stress is reduced by 41.34%, and the statics performance is improved; compared with the original cutterhead structure, the energy flexibility of the optimized cutterhead structure is improved by more than 22.0%, the maximum dynamic response and the minimum dynamic response are reduced by 7.8% and 27.7% respectively, and the dynamic performance is effectively improved. Therefore, the structural variation and reconstruction design method from the view of energy proposed in this paper has great engineering application value and also provides a new idea for the dynamics design of large-size structures represented by tunnel boring machines.关键词：cutterhead panels;structural variation;energy finite element method;topology optimization24|14|0更新时间：2025-07-09
- 摘要：Based on the H-C contact collision model and the Hertz contact collision deformation law, the meshing-in impact force model and analysis method considering cycloid gear tooth profile modification parameters and mechanism design parameters was proposed in the paper with a view to solving the problems such as sudden change of transmission error and increased vibration impact in RV reducers caused by off-line meshing-in impact due to the existence of clearance in the cycloid-pin gear drive mechanism. Firstly, based on the mechanism of how off-line meshing-in impact happened, the theoretical meshing-in point and the actual meshing-in point were determined and the calculation method of elastic torsion angle was clarified. Secondly, based on the H-C contact collision model and the Hertz contact collision deformation law, the meshing-in impact force model of the cycloid-pin gear drive mechanism considering damping force was proposed. Then, by using the multivariate fitting method, the mapping relationship between the design parameters such as cycloid gear radial-moving modification and eccentricity and the meshing-in impact force was constructed, and the influence mechanism of the off-line meshing-in impact characteristics of the cycloid-pin gear drive mechanism was revealed. Finally, the Ansys transient dynamics module was used to simulate the collision dynamic force of the cycloid-pin gear drive mechanism. The results show that the meshing-in impact force increases with the decrease of the negative radial-moving modification amount, the increase of the positive radial-moving modification amount and the decrease of the eccentricity; the maximum impact force error between theory and simulation result is 7.98%, which is in the allowable range and proves the feasibility of the off-line meshing-in impact model. The research results can provide a theoretical basis for the design and optimization of the cycloid-pin gear drive mechanism of RV reducers.关键词：cycloid-pin gear drive;meshing-in impact;eccentricity;radial-moving modification;transient dynamics22|14|0更新时间：2025-07-09
- 摘要：Aiming to meet the requirement of highly accurate indoor positioning for smart mobile devices, a novel acoustic asynchronous positioning method was proposed in this paper based on distance difference and relative velocity measurements. First, combining the measurements of distance difference and relative velocity, a joint estimation model of short time position sequence was established to reduce the cumulative error caused by velocity integration. Then, the LM(Levenberg-Marquardt)algorithm was used to quickly solve the established model. Finally, an iterative optimization process was designed to apply random perturbations to the pre-frame position of the short time position sequence to mitigate the impact of the initial position on the positioning results. Through those methods, accurate indoor acoustic asynchronous positioning can be realized for smart mobile devices under the low density of beacon deployment. The numerical simulation and experimental results show: The proposed method is superior to traditional asynchronous positioning methods in both 2D and 3D positioning scenarios, with higher positioning accuracy and stability and the minimum number of required beacons being reduced to 2 and 3, respectively; the positioning performance of the traditional asynchronous positioning methods gradually approach that of the proposed method as the number of beacons increases; in a 2D positioning scenario with 3 beacons, the positioning accuracy of the proposed method is better than 0.43 m with a 90% probability when the length of the short time position sequence T=2, and better than 0.29 m when T=3. Therefore, the proposed method can achieve both higher positioning accuracy and better positioning stability in conditions with a low beacon deployment density.关键词：indoor positioning;acoustic positioning;asynchronous positioning;time difference of arrival18|12|0更新时间：2025-07-09
- 摘要：The vector controller of the permanent magnet synchronous motor(PMSM)suffers poor dynamic performance when external load disturbance occurs. Therefore, a novel active flux fixed-time sliding mode load disturbance identification method for the PMSM was proposed in this paper. Firstly, based on the definition of active flux, the active flux model of the motor was analyzed, and the reduced-order active flux third-order extended state observer was constructed in combination with the extended state observer theory to reduce the dependence on the motor parameters. Then the virtual control rate and virtual control input of the observer was constructed in combination with the fixed-time sliding mode theory to realize the fixed-time convergence of the current error and improve the observation accuracy and corresponding speed when the load torque changed dynamically. Finally, the observed load torque was fed forward to the current loop controller to realize the accurate observation and compensation of the dynamically changing load torque, and further improve the dynamic performance of the control system. The proposed disturbance identification strategy was verified by numerical simulation: Compared with the traditional sliding mode load torque observer, the fixed-time sliding mode load observer proposed in this paper has a lower steady-state error and better dynamic performance; compared with the uncompensated condition, after FTSMLTO feedforward compensation is adopted, the positive speed overshoot is reduced by about 10.7%, the negative overshoot by about 14.9%, and the overshoot under sinusoidal load by about 25.0%.关键词：permanent magnet synchronous motor;fixed-time consensus;sliding mode load torque observer;state observer;disturbance rejection feedforward compensation29|6|0更新时间：2025-07-09
- 摘要：In order to optimize the transient characteristics of the isolated wind-storage power grid and enhance its anti-interference ability in harsh operation, a combined nonlinear robust control strategy of wind power and energy storage in isolated grids was proposed in the paper. Based on the state feedback exact linearization and robust H∞ optimal control theory and taking into consideration various interference factors(for instance, torque disturbance, power disturbance, voltage disturbance of the synchronous motor)in the system modeling, an exact linearization dynamic model of the isolated wind-storage grid was established by constructing the diffeomorphism nonlinear coordinate transformation, and then a combined nonlinear robust controller of wind power and energy storage was designed. The proposed strategy can help the wind turbine maximize the wind power by maintaining the optimal revolution speed in real time and can keep power generation tracking the load change through the combined control of wind power and energy storage, realizing the multi-objective control. The simulation results show that the proposed combined nonlinear robust control strategy can hold strong robustness to external wind speed and load disturbance. When the external wind speed or the system load changes drastically, the isolated wind-storage grid can promptly and smoothly transition to the steady state under the action of the nonlinear robust controller, which effectively avoids the overshoot and 2—3 oscillations in the adjustment process when using the traditional PI control and significantly improves the transient characteristics of the isolated wind-storage grid. The research can provide a theoretical basis and engineering practice for the combined control of isolated wind-storage grids.关键词：isolated grid;energy storage;exact linearization;nonlinear robust control;combined control31|6|0更新时间：2025-07-09
- 摘要：Aiming at the problem of the low energy storage economy of the separate configuration of integrated energy microgrids, a cost-effective electro-heat hybrid energy sharing model was established in the paper in which multiple integrated energy microgrids shared a single electro-heat hybrid energy storage device. In the research of electricity-heat hybrid energy storage capacity sharing, a hybrid energy storage combination auction method based on multi-item auction theory was adopted: Each microgrid submits multiple sets of different electricity and heat storage capacity requirements and corresponding bidding prices, bids for electrochemical energy storage capacity and heat storage tank capacity respectively, and uses the energy storage capacity to save the costs of purchasing electricity. Energy storage operators determined the outcome of the auction with the goal of maximizing social welfare, that is, how to allocate the energy storage capacity to each microgrid to maximize its utility. In the final fee settlement process, the Vickrey-Clarke-Groves(VCG)mechanism was used to calculate the fees to be paid by each microgrid. Due to the incentive compatibility of the VCG mechanism, each microgrid had no incentive to make false quotations and tended to submit the real bid price, which ensured that the combined auction results had the greatest social welfare. The example results show that in terms of social welfare, the hybrid energy storage portfolio auction proposed in this paper has more advantages than the general shared energy storage model.关键词：combinatorial auctions;energy sharing;hybrid energy storage;incentive compatible;social welfare26|5|0更新时间：2025-07-09
- 摘要：To solve the problem that measurement loss which happens during tracking multiple maneuvering targets by Doppler radar due to Doppler blind zone(DBZ)can jeopardize the performance of the tracker, the minimum detectable velocity(MDV)was introduced into the interactive multi-model generalized labeled multi-Bernoulli(IMM-GLMB)filter and the MDV information was used to suppress the impact of the DBZ on the tracker. Firstly, the interactive multiple model(IMM)algorithm based on the Markov branch merging strategy was adopted to find a solution to the difficulty that the maneuvering target could not be tracked under the condition of a single motion model. Secondly, the detection probability model incorporating the MDV information was introduced into the update equation of the IMM-GLMB filter with the implementation process being detailed, and the MDV and Doppler information were used to improve the performance of the tracker. Finally, an adaptive track start algorithm suitable for the generalized labeled multi-Bernoulli(GLMB)filter was proposed with a view to solving the problem that the current algorithm needs a fixed track start position to track. The simulation results show that the proposed filtering algorithm has better performance under different DBZ widths with DBZ having little impact on the performance of the filter especially when it is small and also sees a 34% improvement in single step running time.关键词：maneuvering multi-target tracking;Doppler blind zone;track initiation;generalized labeled multi-Bernoulli36|21|0更新时间：2025-07-09
- 摘要：Existing attention mechanisms often use fusion or compression to obtain the required information, but this leads to a large quantity of information lost in the spatial or channel dimension. In order to solve this problem, the Spatially Partitioned Attention Module(SPAM), a really effective and lightweight attention module that can help obtain attention without channel fusion or compression, was proposed in the paper. For the input intermediate feature map, the SPAM first adaptively used average pooling and maximum pooling features for feature extraction, replaced the point feature with the local block feature in space to reduce the amount of calculation and used the IN layer and depthwise convolution to capture global spatial attention. Meanwhile, the reconstruction of channel dimension information was directly completed by group convolution. Finally, the interpolation operation was used to obtain overall attention and weight the input feature map. Notably, the SPAM can be easily embedded in various mainstream CNN architectures, and network performance can be significantly improved by increasing a few microparameters and calculations. To demonstrate the effectiveness of the SPAM, numerous experiments were conducted on the ImageNet-1K, CIFAR-100, and Food-101 datasets, and the network's regions of interest were visualized using Grad-CAM. On the ImageNet-1K, CIFAR-100, and Food-101 datasets, the SPAM improved the accuracy of the baseline network by up to about 1.08%, 2.46%, and 1.09%, respectively. The results show that the performance of the network embedded with the SPAM components is greatly improved; compared to other commonly used lightweight attention mechanisms, the SPAM always works better; the SPAM can really induce the networks to pay more attention to the target object regions and accurately improve the expression ability of the networks.关键词：convolutional neural networks;attention mechanisms;image classification;feature extraction43|5|0更新时间：2025-07-09
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Research on the Correlation Between Simple and Complex Movements of Upper Limbs Using Muscle Synergy
摘要：In order to solve the unclear correlation between muscle synergy patterns of simple and complex movements, the method of combining non-negative least square and cosine similarity was utilized to study the correlation between the two types of movements from the perspective of muscle synergy analysis. Firstly, simple and complex upper limb movement paradigms were designed separately and 8-channel surface electromyography(sEMG)signals were recorded from 20 healthy subjects during movement execution. Secondly, muscle synergy patterns for simple and complex upper limb movements were extracted respectively by decoding of 8-channel sEMG signals using non-negative matrix factorization. Then, the non-negative linear coefficients of the linear combination model were calculated using the non-negative least square and the reconstructed motions were constructed based on these coefficients and the synergy patterns of simple movements. Finally, the similarities between the reconstructed motions and complex movements were evaluated by cosine similarity, and the correlation between simple and complex movements was explored. The results show that synergy patterns of complex movements are the preservation and merging of synergy patterns of simple movements. The preservation of synergy patterns indicates that there are shared basic muscle synergy patterns between simple and complex movements, and the merging of synergy patterns indicates that the synergy patterns of complex movements are a linear combination of synergy patterns of simple movements. The research provides a theoretical basis for the study of neuromuscular motor control and a reference for the study of muscle-computer interface technology.关键词：muscle synergy;simple and complex movements;surface electromyography;non-negative matrix factorization43|23|0更新时间：2025-07-09
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