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Numerical investigations of the effects of blade shape on the flow characteristics in a stirred dead-end membrane bioreactor

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Journal of Hydrodynamics 2018年第6期30卷 1143-1152页

作者： Xu-qu Hu Xing-yi Wang Xiu-cheng Lei Xiang Qiu Lin-feng Chen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University College of Science Shanghai Institute of Technology School of Naval Architecture and Ocean Engineering Jiangsu University of Science and Technology

Numerical simulations of turbulent flows in a stirred dead-end membrane bioreactor are performed by using the RNG k-? model based on the finite volume method with the software Fluent. Comparisons of numerical and experimental results confirm the reliability and the feasibility of the constructed model. The flow structures such as the wake flows and the circulation loops in the stirred flows are well simulated. An increase of stirring speed is proposed to minimize the low velocity region. The single vane stirrer is found to be beneficial for biological separations. Results suggest that the increase of the vane number can enhance the mixing effect in the flow domains. However, a circular disk stirrer goes against the formation of vertical circulations. The six-vane stirrer is found to be able to provide a uniform distribution of the high shear stress.

关键词： Turbulent flow stirred flows membrane fouling membrane bioreactor

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Safe Efficient Policy Optimization Algorithm for Unsignalized Intersection Navigation

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 2011-2026页

作者： Xiaolong Chen Biao Xu Manjiang Hu Yougang Bian Yang Li Xin Xu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082 Wuxi Intelligent Control Research Institute(WICRI)of Hunan University Wuxi 214115China College of Intelligence Science and Technology Institute of Unmanned SystemsNational University of Defense TechnologyChangsha 410073China

Unsignalized intersections pose a challenge for autonomous vehicles that must decide how to navigate them safely and *** paper proposes a reinforcement learning(RL)method for autonomous vehicles to navigate unsignalized intersections safely and *** method uses a semantic scene representation to handle variable numbers of vehicles and a universal reward function to facilitate stable learning.A collision risk function is designed to penalize unsafe actions and guide the agent to avoid them.A scalable policy optimization algorithm is introduced to improve data efficiency and safety for vehicle learning at *** algorithm employs experience replay to overcome the on-policy limitation of proximal policy optimization and incorporates the collision risk constraint into the policy optimization *** proposed safe RL algorithm can balance the trade-off between vehicle traffic safety and policy learning *** intersection scenarios with different traffic situations are used to test the algorithm and demonstrate its high success rates and low collision rates under different traffic *** algorithm shows the potential of RL for enhancing the safety and reliability of autonomous driving systems at unsignalized intersections.

关键词： Autonomous driving decision-making reinforcement learning(RL) unsignalized intersection

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Hybrid CFD/FEM-BEM simulation of cabin aerodynamic noise for vehicles traveling at high speed

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Science China(Technological Sciences) 2013年第7期56卷 1697-1708页

作者： WANG YiPing ZHEN Xin WU Jing GU ZhengQi XIAO ZhenYi YANG Xue Hubei Key Laboratory of Advanced Technology of Automotive Components Wuhan University of Technology State Key Laboratory of Automotive Simulation and Control Jilin University State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Wuhan Ordnance Noncommissioned officers School

Flow passing a vehicle may lead to the increase of the cabin interior noise level through a variety of mechanisms. These mechanisms include vibrations caused by aerodynamic excitations and reradiation from the glass panels, exterior noise trans-mitted and leaked through door seals including gaps and glass edge, and transmission of airborne noise generated by the interaction of flow with body panels. It is of vital importance to predict both the flow fields and the acoustic sources around the ve-hicle to accurately assess the impact of wind induced noise inside the cabin. In the present study, an unstructured segregated finite volume model was used to calculate the flow fields in which a hexahedron grid is used to simplify the vehicle geometry.A large eddy simulation coupled with a wall function model was applied to predict the exterior transient flow fields. The mean flow quantities were thus calculated along the symmetry plane and the vehicle's side windows. A coupled FEM/BEM method was used to compute the vehicle's interior noise level. The total contribution of the interior noise level due to the body panels of the vehicle was subsequently analyzed.

关键词： aerodynamic noise computational fluid dynamics large eddy simulation finite element method boundary element method

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Enhancing high-temperature creep resistance of additively manufactured Ti2AlNb alloys via vacuum hot isostatic pressing-induced tailoring of coherent interfaces

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Vacuum 2025年 239卷

作者： Liu, Yaqun Yang, Xujing Jiao, Haowen State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan University Changsha410082 China China Academy of Machinery Science and Technology Group Co. Ltd. Beijing100048 China

This study investigates the microstructural evolution and creep behavior of additively manufactured Ti-22Al-25Nb intermetallic alloys under different post-processing conditions. Selective laser melting (SLM) was employed to fabricate samples, followed by two distinct heat treatments (HT1: 990°C-1h with water quenching + 800°C-2h with air cooling;HT2: hot isostatic pressing at 1200 °C/150 MPa + aging). Microstructural characterization revealed that the HT1-treated sample exhibited a semi-coherent B2/O interface structure with submicron pores and localized compositional segregation, resulting in interfacial dislocation pile-ups and stress concentrations. In contrast, the HIP-treated HT2 counterpart demonstrated fully coherent B2/O interfaces with negligible lattice mismatch (Δa/a −5 h−1, nearly three times lower than the HT1 one (1.7 × 10−4 h−1) at identical conditions, due to the coherent interface-mediated dislocation glide and the suppressed cavity nucleation. The study highlights the critical role of interfacial coherency and defect elimination in enhancing high-temperature creep resistance, providing a microstructure-guided strategy for optimizing additively manufactured Ti2AlNb alloys for aerospace applications. © 2025 Elsevier Ltd

关键词： Hot isostatic pressing

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Hashin Failure Theory Based Damage Assessment Methodology of Composite Tidal Turbine Blades and Implications for the Blade design

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China Ocean Engineering 2018年第2期32卷 216-225页

作者： YU Guo-qing REN Yi-ru ZHANG Tian-tian XIAO Wan-shen JIANG Hong-yong State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University College of Mechanical and Vehicle Engineering Hunan University Strategic Development Department China Three Gorges Corporations

A damage assessment methodology based on the Hashin failure theory for glass fiber reinforced polymer(GFRP)composite blade is proposed. The typical failure mechanisms including the fiber tension/compression and matrix tension/compression are considered to describe the damage behaviors. To give the flapwise and edgewise loading along the blade span, the Blade Element Momentum Theory(BEMT) is adopted. In conjunction with the hydrodynamic analysis, the structural analysis of the composite blade is cooperatively performed with the Hashin damage model. The damage characteristics of the composite blade, under normal and extreme operational conditions,are comparatively analyzed. Numerical results demonstrate that the matrix tension damage is the most significant failure mode which occurs in the mid-span of the blade. The blade internal configurations including the box-beam, Ibeam, left-C beam and right-C beam are compared and analyzed. The GFRP and carbon fiber reinforced polymer(CFRP) are considered and combined. Numerical results show that the I-beam is the best structural type. The structural performance of composite tidal turbine blades could be improved by combining the GFRP and CFRP structure considering the damage and cost-effectiveness synthetically.

关键词： composites tidal current turbine blade damage assessment tidal energy Hashin failure theory blade design

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Path Tracking Controller design of Automated Parking Systems via NMPC with an Instructible Solution

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 353-367页

作者： Liang Chen Zhaobo Qin Manjiang Hu Yougang Bian Xiaoyan Peng State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China Wuxi Intelligent Control Research Institute of Hunan University Wuxi 214115China

Parking difficulties have become a social issue that people have to *** parking system is practicable for quick par operations without a driver which can also greatly reduces the probability of parking *** paper proposes a Lyapunov-based nonlinear model predictive controller embedding an instructable solution which is generated by the modified rear-wheel feedback method(RF-LNMPC)in order to improve the overall path tracking accuracy in parking ***,A discrete-time RF-LNMPC considering the position and attitude of the parking vehicle is proposed to increase the success rate of automated parking ***,the RF-LNMPC problem with a multi-objective cost function is solved by the Interior-Point Optimization,of which the iterative initial values are described as the instructable solutions calculated by combining modified rear-wheel feedback to improve the performance of local optimal ***,the details on the computation of the terminal constraint and terminal cost for the linear time-varying case is *** closed-loop stability is verified via Lyapunov techniques by considering the terminal constraint and terminal cost ***,the proposed RF-LNMPC is implemented on a selfdriving Lincoln MKZ platform and the experiment results have shown improved performance in parallel and vertical parking *** Monte Carlo analysis also demonstrates good stability and repeatability of the proposed method which can be applied in practical use in the near future.

关键词： Automated parking Path tracking controller Nonlinear model predictive control Monte Carlo analysis

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Trajectory tracking control of autonomous heavy-duty mining dump trucks with uncertain dynamic characteristics

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Science China(Information Sciences) 2023年第10期66卷 246-262页

作者： Liang CHEN Zhaobo QIN Manjiang HU Hongbo GAO Yougang BIAN Biao XU Xiaoyan PENG State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Wuxi Intelligent Control Research Institute of Hunan University Department of Automation University of Science and Technology of China

The proportion of mines using autonomous mining trucks is still very low at present. To promote the development of intelligent mining, it is urgent to proceed with the drive-by-wire modification to common mining trucks and design a motion control algorithm considering uncertain dynamic *** paper proposes a trajectory tracking control method for autonomous heavy-duty mining dump trucks(AHMDTs) with uncertain dynamic characteristics. In this method, a driving/braking force compensation algorithm based on an inverse dynamic model is designed to guarantee accurate longitudinal control with less control gain tuning. Using road curvatures, a modified rear-wheel position feedback control method is proposed to deal with reverse-path tracking, which can simultaneously reduce the lateral error and yaw angle error. A modified Stanley controller considering the collaborative preview based on speed and curvature is constructed to achieve accurate path tracking in the forward gear. Moreover, the proposed method focuses on the practice of trajectory tracking control in an open-pit mine condition with the adverse effects caused by uncertain vehicle dynamics, huge variable load, and large actuator lag. Real vehicle tests show that the proposed methodology can control AHMDTs with a low tracking error.

关键词： vehicle control trajectory tracking control driving/braking force compensation rear-wheel position feedback

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Greatly enhanced corrosion/wear resistances of epoxy coating for Mg alloy through a synergistic effect between functionalized graphene and insulated blocking layer

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Journal of Magnesium and Alloys 2024年第1期12卷 332-344页

作者： Z.Y.Xue X.J.Li J.H.Chu M.M.Li D.N.Zou L.B.Tong School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various *** conventional epoxy coating easily forms many intrinsic defects during the solidification process,which cannot provide sufficient *** the current study,we design a double-layer epoxy composite coating on Mg alloy with enhanced anti-corrosion/wear properties,via the spin-assisted assembly *** outer layer is functionalized graphene(FG)in waterborne epoxy resin(WEP)and the inner layer is Ce-based conversion(Ce)*** FG sheets can be homogeneously dispersed within the epoxy matrix to fill the intrinsic defects and improve the barrier *** Ce film connects the outer layer with the substrate,showing the transition *** corrosion rate of Ce/WEP/FG composite coating is 2131 times lower than that of bare Mg alloy,and the wear rate is decreased by~90%.The improved corrosion resistance is attributed to the labyrinth effect(hindering the penetration of corrosive medium)and the obstruction of galvanic coupling *** synergistic effect derived from the FG sheet and blocking layer exhibits great potential in realizing the improvement of multi-functional integration,which will open up a new avenue for the development of novel composite protection coatings of Mg alloys.

关键词： Mg alloy Functionalized graphene Epoxy coating Corrosion/wear resistance Blocking layer

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Effects of working parameters on gasoline engine exergy balance

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Journal of Central South University 2013年第7期20卷 1938-1946页

作者： LIU Jing-ping FU Jian-qin FENG Ren-hua ZHU Guo-hui Research Center for Advanced Powertrain Technology Hunan University Changsha 410082 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body (Hunan University) Changsha 410082 China

To improve the energy utilization efficiency of internal combustion （IC） engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure （BMEP） at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.

关键词： gasoline engine exergy balance waste heat recovery thermal efficiency energy conservation

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Lightweight, Strong and Stiff Lattice Structures Inspired by Solid Solution Strengthening

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Materials 2025年第9期18卷 1984页

作者： Xiao, Peijie Xu, Shiwei Chen, Longbao Ruan, Zhisheng Zeng, Zhuoran Xiao, Zhi Li, Jianyu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Suzhou Research Institute of Hunan University Suzhou215131 China

In engineering design, introducing lattice structures offers a cost-effective method for reducing weight while enhancing load-bearing efficiency, compared to merely enhancing the material strength of a solid component. Among the various lattice structure configurations developed thus far, the strength and stiffness of these structures remain significantly below their theoretical limits. This study demonstrates that the theoretical limits of strength and stiffness in lattice structures can be achieved by mimicking the solid solution strengthening mechanism in materials science. This innovative structure achieves the highest load-bearing efficiency to date and is applicable to lattice structures of any geometric configuration. The introduction of the sosoloid structure, a lattice structure with struts reinforced along the loading direction, increases the theoretical limits of lattice strength and stiffness by 20% and 27.5%, respectively, compared to traditional uniform lattice structures. The most effective enhancement is observed when sosoloid structures exhibit the highest material utilization rate and optimal spatial layout. These findings offer a general approach to achieving high load-bearing structures and have broad application prospects in lightweight and high-strength structures, such as human bone design and energy absorption. © 2025 by the authors.

关键词： Reinforcement

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