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In the production of polyester fibers from recycled polyethylene terephthalate (rPET), the drying and crystallization of plastic bottle flakes are crucial for ensuring the consistency and strength of the finished fibers. Traditionally, rPET production lines still rely on vacuum drum dryers, which have been suffering from issues including agglomeration, uneven heating, and high energy demand. In this work, we developed a novel continuous system that is capable of achieving a total throughput of 1300 kilograms per hour. The design consists of a pulsating fluidized-bed crystallizer and two cylindrical drying towers operating in parallel. Structural performance of the main systems was analyzed using finite element analysis under material load, thermal expansion, and internal air pressure. Airflow behavior and temperature distribution inside the units were studied using Computational Fluid Dynamics (CFD) models, where the flake bed was treated as a porous medium based on experimental bulk density and pressure drop. Results showed that the drying tower maintained a minimum safety factor above 3 under full-load conditions, while the crystallizer also remained well within allowable stress limits. Additionally, flow-field analysis results indicated stable countercurrent airflow, adequate mixing near the inlet region, as well as acceptable axial temperature gradients for moisture removal below 50 ppm. Compared with conventional drum drying, we believe the continuous configuration simplifies operation and reduces heat loss. Our design approach has been combined with analytical calculations on structural and flow simulation, and can be beneficial when applied to similar rPET drying applications.
Wu, Ye, Wu, Tianqi, Ge, Yuchen, Ni, Hongjun, Tan, Linwei, Lv, Shuaishuai
Conventional types of wipers are characterized by some consistent disadvantages, such as huge uncleared blind spots (up to 40 percent of the target area), limited wiping functionality, and great dynamic visual interference. Due to the intensive full-field visibility demands of autonomous driving, this paper will introduce a new linear reciprocating wiper that will be driven by a ball screw. In particular, one of the prototypes of such a system is designed based on a Dongfeng heavy-duty truck, according to which the traditional oscillatory movement is converted into a horizontal directional movement by a ball screw. This is powered by a motor of 24 V drive with a worm gear reducer to give the force needed to achieve the horizontal reciprocating motion of the wiper blade assembly over the windshield. For the intelligent control module of the proposed lateral linear wiper system, a special intelligent control system is developed based on the principle of CAN bus communication and multi-sensor fusion. Both a rain sensor and a proportional-integral-derivative (PID) algorithm allow the system to achieve adaptive control of wiper speed and apply to various modes, including intermittent wiping, low-speed wiping, and high-speed wiping.
Dong, Xingzhuang, Hu, Yanxingyu, Li, Jincheng, Xu, Tongqiang, Wu, Liying
To address low energy recovery efficiency and inaccurate torque distribution of regenerative braking in electric vehicles, this paper proposes an optimized fuzzy control strategy for regenerative braking based on an improved ant colony algorithm. The design focuses on using the battery state of charge, real-time vehicle speed, and braking intensity as fuzzy control inputs, with the regenerative braking ratio as the output. By employing the improved ant colony algorithm to dynamically optimize the parameters of the fuzzy controller, the accuracy of electric motor braking force distribution is effectively improved; Building on this foundation, the introduction of the Elite Ant Guidance Algorithm enhances the speed of adaptive pheromone updates and dynamic path selection, thereby improving regenerative braking energy recovery efficiency. A MATLAB/Simulink simulation model was developed, and comparisons under the NEDC and UDDS test cycles demonstrated that, compared to traditional fuzzy control strategies, the optimized algorithm increases energy recovery efficiency by 12.8% and 8.1%, respectively, confirming the effectiveness and validity of the improved control strategy.
Yang, Zijiang, Zhang, Wei, Zhang, Jihong, Qi, Ye, Zhang, Zilei
Based on the Jacobian tensor and small displacement tensor theories, this paper establishes a three-dimensional tolerance chain analytical model for manufacturing and assembly errors in planetary gearboxes and proposes three methods for managing tolerance accumulation paths. Through tolerance analysis, the cumulative pitch error is quantified and incorporated into the nonlinear dynamic model of the planetary gearbox to determine the time-varying meshing force between the ring gear and planetary gear. This enables calculation of the theoretical load distribution coefficient while accounting for three-dimensional tolerance effects. To validate the model’s accuracy, a dedicated test bench was constructed, and dynamic stresses were measured using a root strain gauge array; the experimental load distribution coefficient was then derived. Comparison of simulation and experimental results shows that the deviation in the load distribution coefficient is only 7.4%, strongly confirming the reliability of the three-dimensional tolerance-dynamics coupled model. This study represents the first closed-loop verification from tolerance propagation to system-level load distribution, providing a theoretical foundation for tolerance design optimization and load distribution performance enhancement in high-precision planetary gearboxes.
Yu, He, Duan, Jiandong, Zhang, Jing, Shi, Wankai
In order to improve the quality of the tunnel cross-section formation and the cutting efficiency of the drilling machine, this paper established a horizontal swing cutting model for the cutting head and conducted a simulation analysis of the spatial movement trajectory of the cutting teeth. A finite element simulation model of the cutting teeth cutting coal and rock was established using the Abaqus/Explicit software. The simulation data were processed and statistically analyzed using MATLAB software. The influence patterns of variable cutting parameters and coal and rock properties on the quality of the tunnel cross-section formation and the cutting efficiency of the drilling machine were studied. Thus, the dual-objective optimal cutting parameters for the automatic cutting control of the drilling machine were determined, guiding the cutting head to perform coal and rock cutting operations. The research on the influence patterns on the coal and rock cutting efficiency of the cutting teeth of the tunneling machine can also provide references for solving problems in the swinging state control of the cutting arm and the correction of the cutting head trajectory.
Qin, Lei, Sun, Changyuan, Li, Xiangshuai, Sun, Xiaolin, Li, Longjie, Lyu, Wenjun
To overcome the trade-off between airflow rate and efficiency in a multi-blade centrifugal fan for automotive air-conditioning systems, as well as the low optimization efficiency of conventional simulation- or experiment-based approaches resulting from the large number of impeller design parameters, a surrogate-model-based optimization framework coupled with an intelligent optimization algorithm is proposed for impeller design. Latin hypercube sampling was employed to generate 120 samples within the design space, and an XGBoost model was integrated with a Bayesian optimization strategy to perform the optimization process. Validation results indicate that the prediction error of the surrogate model is less than 3%. Under the final optimized impeller configuration, the airflow rate is increased by 22% at the design operating condition, while the total pressure efficiency is improved by approximately 20%, satisfying the prescribed design requirements.
Yan, Yaqin, Yue, Chen
As green development has become a global unified strategy, major developed countries in the world have successively announced their ambition to achieve carbon neutrality in this century. The new energy vehicle and traction battery industry has ushered in a high-quality development moment, and the safety of traction batteries has also been widely valued worldwide. As the traction battery is mainly arranged at the bottom of the vehicle, enhancing the operational safety of new energy vehicles necessitates a breakthrough in performance testing for bottom-impact protection. It is essential to develop a robust evaluation methodology that can accurately and efficiently evaluate the extent of damage inflicted on the battery system following a bottom impact or collision. Based on the bottom impact experiment of a typical traction battery pack, this paper studies the damage morphology and damage mechanism of the bottom impact. By integrating finite element mechanical simulations, it provides a detailed analysis of the evolving mechanical states across different zones of the battery pack during the impact event. The findings contribute to enhancing safety protection strategies for traction batteries in bottom impact scenarios and offer crucial support for evaluating the post-impact safety performance of new energy vehicles.
Yan, Pengfei, Han, Liqiong, Chen, Liduo, Wang, Fang, Ma, Tianyi, He, Gaiyun, Liu, Lei
This paper proposes an electric tightening tool for screw tightening in confined spaces during aero-engine assembly. By combining a gear with a curved rack, the tool converts the motor’s rotary motion into the swing motion of the tool head, thereby addressing torque transmission problems in narrow radial spaces. The tool head features an openable clamping mechanism to facilitate operation. Finite element analysis is used to evaluate the stress distribution and strain characteristics of key components under representative loading conditions. The results show that, under the specified working conditions, the stresses and deformations of the key components remain within reasonable ranges, and the structural strength meets the requirements for use.
Bu, Xin, Feng, Junping, Peng, Shuhao, Yang, Yinfei
Because of the imprecision of length quantification in the manufacturing of flat wire windings for flat wire motors, empirical allowances have long been a common practice in production, which in turn leads to considerable material waste and elevated production costs. This paper presents an integrated solution that fuses material experiments, reverse engineering, simulation iteration and parametric design, realizing accurate prediction and quantitative calculation of winding forming length. First, high-precision elastic-plastic constitutive relationships of flat wires are acquired through room-temperature uniaxial tensile tests. On this basis, reverse engineering is applied to derive the initial geometric characteristics and process motion paths of flat wire windings from the 3D model of finished products. Next, an innovative closed-loop iterative compensation algorithm is constructed, with the forming height of the innermost flat wire layer serving as an absolute reference; finite element simulation is then utilized to dynamically optimize the forming length of each flat wire layer. Finally, a parametric design system with a visual interactive interface is developed, which enables an intelligent workflow where precise cutting lengths and equipment motion curves are automatically generated upon input of key design parameters. Production validation results show that this method drastically reduces the length allowances of flat wires, markedly lowers the production scrap rate, and shortens the process debugging cycle of new motor models by more than 80%.
Li, Wenbin, Zhu, Ye
In recent years, the sales volume of new energy vehicles (NEVs) in China has maintained a steady growth trend, and consumers have paid increasing attention to vehicle range. Against this backdrop, the demand for lightweighting of various core components of NEVs has significantly increased. As a key component of automobiles, the wheel hub accounts for a relatively large proportion of the unsprung mass, and its lightweighting is of great significance for improving the driving range and enhancing vehicle performance. In this paper, sunflower and bridge truss are integrated as design elements, and a small-sized new energy sports utility vehicle (SUV) is selected as the reference vehicle model to design a lightweight wheel hub. Creo is used for 3D modeling of the wheel hub, and static stress, radial fatigue, bending fatigue, and modal simulations are performed in ANSYS Workbench. The results show that all wheel hub performance indicators meet the service requirements. Meanwhile, the quality evaluation indicates that the weight of the designed wheel hub is 10.95 kg, which is 3.90 kg lighter than the original wheel hub, representing a weight reduction of 26.3% compared with the original one, thus meeting the lightweighting standards.
Li, Chang
In the modeling process, existing auto parts demand forecasting methods often fail to clearly distinguish structural differences at the demand-frequency level, which results in limited adaptability in real scenarios characterized by sparse demand and a complex category structure. In response to the above problems, this paper proposes a category-aware Transformer framework for auto parts demand forecasting. To explicitly represent demand differences across frequency-based accessory groups and to reduce training bias caused by long-tail sample imbalance, the framework first constructs frequency categories based on statistical demand characteristics and incorporates them into the model as embedding-based structural priors. It then designs a category-perception attention mechanism within the Transformer to guide differentiated modeling of category-related temporal dependencies. At the same time, in order to improve the expression ability of sparse and nonlinear disturbances, this paper introduces a nonlinear mapping module at the prediction end and uses a weighted loss function based on sample distribution to constrain the training target. Experimental results on three real auto-parts demand datasets from Dongfeng Automobile Co., Ltd. show that the proposed method outperforms five benchmark models in terms of RMSE and MAE, with especially strong performance in predicting intermediate-frequency and long-tail parts.
Yi, Yuxuan, Wang, Xiaodong, Yang, Wei, Cai, Yonghua
Reliable anchoring of slip is essential for preventing axial slippage of pipeline plugging robots under high-pressure plugging conditions. However, excessive tooth penetration may induce furrow formation, local plastic deformation, and hard-contact damage on the inner wall of the pipeline. To balance anchoring capacity and pipe-wall protection, this study establishes a mechanical model for the slip–pipe interaction and analyzes the effects of key structural parameters on slip anchoring performance. The self-locking condition between the slip and slip bowl is first derived, and the minimum equivalent friction coefficient required for stable anchoring is determined. Subsequently, an explicit finite element model of the slip anchoring process is developed to evaluate the influence of bevel angle, tooth profile angle, and curvature radius on the von Mises stress and equivalent plastic strain of both the slip and the pipe wall. Based on the simulation results, an orthogonal parameter optimization scheme is conducted to identify the optimal structural combination. The results show that the optimized slip structure, consisting of a 20° bevel angle, a 90° tooth profile angle, and a 150 mm curvature radius, can effectively reduce pipe-wall damage while maintaining reliable anchoring performance. This study provides a theoretical and numerical basis for the structural design and optimization of anchoring slip in pipeline plugging robots.
Wang, Mingkuan, Zhang, Enchao, Gao, Ang, Shao, Hongyuan, Zhang, Shimin, Zhu, Xiaoxiao
An SSS clutch is incorporated into the shaft system of the NCB steam turbine in the gas-steam combined cycle unit. The benefit of this specific design is that the shaft system of the NCB steam turbine can disengage from and engage with the LP rotor during operation, enabling rapid and flexible adjustment between power generation output and heat supply. However, this mode of operation presents some special vibration issues in the shaft system. Analysis of the shaft vibration fluctuations that occur in NCB steam turbines before and after operating mode transitions indicates that this issue arises because the random engagement position of the SSS clutch induces changes in the shaft train’s balance and alignment conditions. Based on the measurement principle of shaft vibration phase and the dual keyphasor measurement system of NCB steam turbines, this paper proposes a novel methodology for determining the optimal engagement position of SSS clutches. This approach establishes quantitative correlations between shaft vibration characteristics and clutch engagement positioning, thereby enabling precise identification of the optimal engagement configuration. The research conclusions provide operational guidance for power plants to optimize shaft vibration in NCB steam turbines.
Song, Tongtong, Song, Yajun, Zhang, Wei, Si, Paiyou, Gao, Yibo
During cornering-braking maneuvers, an excessively high braking torque can consume a substantial portion of the available tire-road friction and cause insufficient frictional capacity to satisfy the lateral force demand generated by cornering. As a result, the vehicle may experience stability degradation and, in severe cases, lose control, potentially causing accidents. In this study, an AMESim-based vehicle dynamics model is developed, and yaw rate and sideslip angle are adopted as the primary evaluation indices to characterize steering-braking behavior. Under conditions of a fixed turning radius and initial braking speed, the critical braking force was simulated and analyzed. Additionally, the critical steering wheel angle was examined under conditions of a fixed braking torque and steering speed. The results indicate that if either the braking force or the steering wheel angle exceeds its critical value, the vehicle will lose stability during combined steering and braking.
Ma, Lianglin, Yi, Bingjun, Hu, Yang
Considering the impact of machining errors in the mass production of car doors, uncertainty factor analysis is introduced to achieve the three-in-one optimization goal of “lightweight-performance-reliability”. This paper takes a car door as the research object. First, its finite element model is established, and analyses of upper torsion, lower torsion, vertical, and belt line stiffness working conditions, as well as modal analysis, are carried out to obtain the door’s stiffness and modal performance data. Taking the thickness of the door sheet metal parts as the design variable, an RBF surrogate model is established. The NSGA-II algorithm is used to carry out reliability optimization with the stiffness under four working conditions, the first-order torsional mode, and the Six Sigma reliability level as constraints, and with the minimization of door mass and maximization of the first-order bending mode as objectives. The research results show that while meeting the reliability requirements and achieving weight reduction of the door, the performance of the door is also improved.
Wei, Yansai, Shen, Yongfeng, Wan, Huawei, Li, Dan
Low-altitude economy has already become an important strategic engine for high-quality development as a symbol of new productive forces. The impact of ESG performance on corporate value within the low-altitude economy (a strategic emerging industry), as well as its dual effects and situational specificities, is systematically and empirically examined in this paper using panel data from Chinese A-share listed companies from 2018 to 2023. The results show that the ESG performance of “low-altitude economy” enterprises has a significant impact on company value through two channels: investment in R&D and obtaining more government subsidies. Analyst coverage might be contradictory; too much analyst coverage may even counteract the advantage of ESG performance. Our results also reveal significant heterogeneity patterns. Value-enhancing effects of ESG are greater in low-pollution sectors, technology-based enterprises, non-State-owned companies, and companies located in central and western China. To foster sustainable, high-quality company business, this paper provides suggestions for implementing ESG and conceptually elaborates on how the low-altitude economy influences company ESG performance.
Lv, Xiaonuo, Chu, Yanchang
In high-end aerospace mission scenarios such as distributed sensing and tactical reconnaissance, path planning for multi-UAV cooperative formation flight has become an indispensable core component of mission systems. However, a key unresolved technical bottleneck remains: how to achieve an optimal balance between strictly maintaining the UAV formation’s preset geometric configuration and realizing collision-free, flexible flight in dynamically changing complex environments. Multi-Agent Reinforcement Learning (MARL) can theoretically solve this coupled optimization problem, but the control instructions generated by the existing mainstream MARL methods often have high-frequency fluctuation issues. Direct deployment of these fluctuating commands on physical UAV hardware will increase alternating stress on mechanical structures, raise the risk of motor overheating, and significantly boost battery energy consumption. These problems directly restrict the engineering application of such methods. To address the above challenges, this paper proposes a robust control framework that accounts for UAV physical characteristics to solve the model mismatch between simulation environments and real flight scenarios during carrier-based UAV deployment. Firstly, to improve the learning efficiency of the algorithm and avoid the cold start problem in the initial training stage, this paper introduces the Adaptive Curriculum Learning (ACL) method. Unlike the fixed-difficulty training mode, ACL can dynamically adjust the environmental complexity based on the real-time task performance of the UAVs. It first allows agents to master basic formation maintenance skills, before training is gradually transitioned to more complex tasks such as navigation in intricate environments. Additionally, considering the computational limitations of the onboard embedded processors of UAVs, this paper only integrates the Graph Attention Network (GAT) into the centralized Critic network of the centralized training and decentralized execution (CTDE) framework. The core advantage of this design is that the system no longer solely relies on distance as the judgment basis but assesses the influence of adjacent UAVs based on the collision risk level. This not only improves the accuracy of value estimation, but also does not compromise the response speed of local control instructions- a feature that is crucial for the real-time requirements of UAV flight control. The proposed method was tested and validated in a high-fidelity simulation environment built in strict compliance with UAV kinematic constraints. The experimental results fully demonstrate its superiority: in dense obstacle areas, the success rate of the task reached 80.4%; compared with the aggressive baseline method, the jerk was reduced by 10.9%. Most importantly, the flight trajectories generated by this framework are smooth and adaptable to actual flight conditions, and the corresponding control commands can be directly deployed on real flight controllers without additional parameter adjustments. This result demonstrates that the proposed framework achieves substantial technical progress in enhancing the autonomous response capabilities of UAV clusters to complex scenarios.
Huang, Xingyu, Zhang, Jiyu, Jiang, Yanshu, Fan, Yuhang
This paper aims to empirically examine the dynamic correlation mechanism based on market signals between the two strategic emerging industries, namely the new energy vehicles (NEVs) and the low-altitude economy (LAE), from the perspective of the capital market. In response to the challenges of lagging and missing statistical data of emerging industrial entities, this study innovatively views the stock market indices as a “forward-looking signal” of industry dynamics, and constructs a four-step analytical framework of “long-term trend synergy, short-term fluctuation correlation, long-term equilibrium and causal leadership, and key event resonance”. Based on monthly data from January 2017 to December 2025, the study comprehensively uses methods such as cointegration tests, vector error correction models, and the Granger causality tests for analysis. The results show three main findings. Firstly, the long-term trends of the two industry indices are highly synchronous. Secondly, their short-term market returns show a significant positive correlation (r = 0.637). The cointegration test indicates that there is a long-term equilibrium relationship between the two. The Granger causality test further reveals a bidirectional prediction relationship: the impact of the LAE industry on the NEV industry is more significant (p < 0.05), and the NEV industry also has a predictive effect on the LAE industry (p < 0.1). Finally, these two industries show significant market resonance when facing common industrial policies. This study provides high-frequency evidence from the capital market for understanding the statistical co-movement between these two industries and provides methodological references for the study of the correlation of emerging industry linkages in the period of data scarcity.
Li, Yifan
While Unmanned Aerial Vehicles (UAVs) hold immense potential for transforming the low-altitude economy, developing an agent that combines both intelligence and flexibility remains a significant challenge. To this end, we propose a novel aerial navigation system, Aeroseek, to search for executable paths that coherently transition from cognitive understanding to physical movement, enabling more autonomous and flexible navigation with instruction guidance. Specifically, given a navigation instruction, we follow a fast-andslow thinking procedure inspired by human pilots by breaking down complex decisions into manageable sub-tasks and initiating motion planning immediately upon the completion of each sub-task for realtime movement. By integrating a multi-branch Chain-of-Thought, Aeroseek is capable of combining reasoning with spatial recognition and self-verification to search for robust sub-goals under expected constraints. For sub-goal navigation, we introduce Online Kinodynamic Monte-Carlo Path Planning (OnKi-MCPP), a novel motion planning approach handling both kinodynamic constraints and path search, while ensuring obstacle avoidance for UAVs. Benefiting from the proposed two-tier searching protocol, Aeroseek demonstrates comprehensive capabilities in processing complicated instructions and adapts to dynamic aerial conditions. Extensive experiments demonstrate the advantages of Aeroseek across tasks of varying complexity.
Luo, Guoan, Xu, Tian, Zhou, Jiacong, Wang, Xianyun
This paper describes an intelligent unmanned aerial vehicle (UAV) system that automates red pine cone harvesting in dense forests to mitigate the safety and inefficiency of traditional manual harvesting. The suggested system combines multi-sensor fusion perception, variable-stiffness rigid-flexible composite manipulator, and smart path planning into a single aerial harvesting system. To create a three-dimensional model of the environment and robust cone detection under complicated lighting conditions and extreme canopy occlusion, a heterogeneous sensor suite such as LiDAR, depth cameras, and inertial sensors is used. According to the results of fused perception, collision-free approach paths are created to lead the UAV safely to target cones in limited three-dimensional spaces. One of the significant contributions of this work is the iterative design and optimization of a dedicated harvesting manipulator to be used in aerial forestry operations. A comparative analysis of various structural designs leads to the creation of a rigid flexible composite manipulator with an effective workspace diameter of 1.8 m and adequate stiffness to reduce the effects of the downwash of the UAV rotor. The disturbance-assisted harvesting strategy is adopted by the system, which enables efficient dislodgement of cones without requiring accurate grasping. The proposed technical route is proven to be feasible based on laboratory experiments and initial field tests carried out in real forest settings. It has been experimentally proven that the combined system can effectively perform autonomous harvesting cycles, including target recognition, navigation, and cone dislodgement, thus offering a practical technical paradigm of intelligent and safe forestry harvesting applications.
Shi, Shuaiqi, Du, Yisheng, Li, Xiang, Wang, Weidong
In the process of design and verification of the aircraft ice protection system, a prediction model of ice protection system performance based on Severity Index(IPSI) is proposed, which quantifies the relationship between input and output energy of the ice protection system. In this research, a theoretical calculation method is developed, and the water total collection coefficient and convective heat transfer coefficient on the skin surface were obtained using CFD calculations and rapid neural network prediction methods. The consistency between IPSI and ice protection system performance is verified through an aircraft wing ice protection wind tunnel test. The results show that the lower the slat skin temperature in the ice protection area, the higher the IPSI value, which means the more severe the ice protection system performance. The ice protection performance severity analysis method is carried out for the cases in the CCAR/FAR/CS-25 continuous maximum(CM) envelope of an aircraft, and the IPSI values of each case at some altitudes are calculated, as well as the distribution of the ice protection system performance severity cases in the CM altitude-temperature envelope. The ice protection system performance severity cases are not the highest or lowest atmospheric static temperature in the CM envelope, in which atmospheric static temperature ranges from -8°C to -23°C from low altitude (1500 ft) to high altitude (22000 ft). When the flight speed is constant, and the atmospheric static temperature is gradually reduced, the IPSI value decreases. When the atmospheric static temperature is constant, and the flight speed increases gradually, the IPSI value increases. The influence of water evaporation heat transfer on ice protection performance severity is greater than that of convection heat transfer. The total air temperature for the most severe condition is always 0°C at every altitude. The IPSI calculation model can be used to quickly predict the severity of ice protection system performance in other ice protection areas of aircraft, even wind blades.
Hu, Weixue
Aiming at the core problems of abrupt changes in dynamic characteristics and poor smoothness in mode switching during the cross-medium operation of amphibious wing-in-ground (WIG) craft, this paper develops an intelligent switching and control system based on multi-sensor fusion. The system integrates measurement data from the Global Navigation Satellite System (GNSS), Inertial Measurement Unit (IMU), and Light Detection and Ranging (LiDAR) to construct a state observation module for mode switching decision-making. On this basis, a fuzzy switching logic centered on flight altitude and sea state characteristics is proposed, and a hybrid control strategy combining Linear Quadratic Regulator (LQR) and Proportional-Integral-Derivative (PID) is designed to realize the smooth transition between water surface and flight modes. Numerical simulations conducted in Python demonstrate that the proposed control scheme can accurately determine the mode switching timing, stabilize the pitch angle fluctuation within ±3° during the transition process, and effectively enhance the ability of WIG craft to operate autonomously and stably of the WIG craft in complex sea conditions.
Zhang, Qihao, Yan, Yifei, Cao, Fengshuo, Xiong, Yueling, Liu, Qing, Deng, Yanpeng, Wu, Peng
Consumable spare parts for civil aircraft are characterized by intermittent demand patterns. Constrained by long order replenishment cycles, traditional single-step demand forecasting struggles to effectively support inventory decisions. Moreover, research on intermittent demand forecasting primarily focuses on single-step, short-term cycle predictions, while multi-step forecasting using advanced deep learning methods remains in its early stages. To address this issue, this study introduces a multi-step forecasting approach based on the Transformer architecture, employing a MIMO strategy to achieve long time series forecasting for intermittent demand. The model is validated using a dataset from an airline maintenance base consisting of 360 intermittent demand items. A comparative analysis is conducted against three traditional time series models (SES, Croston, and SBA) and several neural network architectures (FNN, GRU, and LSTM). The performance of different methods was compared using six evaluation metrics. Results demonstrate that the Transformer consistently delivers outstanding performance across various forecast horizons. Notably, in long-horizon forecasting tasks, the model’s advantage in prediction accuracy becomes increasingly significant as the forecast step increases.
Zhang, Zhaomin, Zhao, Xin, Zhang, Jian, Fu, Weifang
To address the complexity of the influence of expansion-section geometry on the thrust performance of solid rocket motor nozzles and the low efficiency of numerical-simulation-based optimization, this study proposes a deep-learning-based method for rapid nozzle thrust prediction. With a representative 70-lb BATES nozzle as the research object, the expansion-section contour is parameterized using cubic spline functions. Combined with Latin hypercube sampling and two-dimensional inviscid numerical simulations, a nozzle geometry– thrust dataset covering a wide range of contour characteristics is constructed. On this basis, surrogate models based on a fully connected neural network, a one-dimensional convolutional neural network, and a two-dimensional convolutional neural network are developed, and the applicability of different network architectures to the nozzle thrust prediction task is systematically compared. The results demonstrate that convolutional neural networks outperform fully connected networks in terms of geometric feature representation capability and prediction stability. In particular, by explicitly modeling the spatial structural features of the nozzle contour, the two-dimensional convolutional model achieves a coefficient of determination close to unity on the test set, with an average relative error of 0.03%. Further hyperparameter sensitivity analysis clarifies the effects of batch size, number of training epochs, and learning rate on model convergence behavior and generalization performance. This work provides a feasible technical support for rapid thrust evaluation and efficient optimization-oriented nozzle design.
Yuan, Yuan, Wu, Wei-tao, Hua, Yue