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Design method with controllable velocity direction at throat for inward-turning inlets

Chinese Journal of Aeronautics 2019年第6期32卷 1403-1415页

作者： Wenyou QIAO Anyuan yu Wei GAO Weixing wang Research Center of Combustion Aerodynamics Southwest University of Science and TechnologyMianyang 621010China Jiangsu Province Key Laboratory of Aerospace Power System Nanjing 210016China Science and Technology on Scramjet Laboratory of Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In the design of a hypersonic inward-turning inlet by applying the traditional basic flowfield, a reflected shock-wave is formed in the isolator due to the continuous reflection of the cowlreflected shock wave in the basic flow-field, which interacts with the boundary layer to produce a considerable influence on the performance of the inlet. Here, a basic flow-field design method that can control the velocity direction at the throat section is developed, and numerical simulations are conducted to demonstrate the effectiveness of this method. The method presented in this paper can achieve the absorption of the reflected waves at the shoulder of the basic flow-field by adjusting the variation law of the center radius in the basic flow-field, and a smooth transition between the compression surface and the isolator can also be produced. The Mach number and total pressure recovery coefficient of the inlet designed according to this method are 3.00 and 0.657, respectively, at design point(the incoming flow Mach number Ma1= 6.0). The results show that with this method, the inlet can efficiently weaken both the reflection of the shock wave and the interaction between the boundary layer and the reflected shock waves, which improves the aerodynamic performance of the inlet.

关键词： Hypersonic Inverse design Inward-turning inlet Method of characteristic Shock wave

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Theoretical analysis of the sound absorption characteristics of periodically stiffened micro-perforated plates

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Acta Mechanica Sinica 2014年第5期30卷 714-726页

作者： Hai-An Zhou Xiao-Ming wang yu-Lin Mei School of Mechanical Engineering Shandong University of Technology School of Mechanical Engineering Dalian University of Technology School of Automotive Engineering Dalian University of Technology

The vibro-acoustic responses and sound absorption characteristics of two kinds of periodically stiffened micro-perforated plates are analyzed theoretically. The connected periodical structures of the stiffened plates can be ribs or block-like structures. Based on fundamental acoustic formulas of the micro-perforated plate of Maa and Takahashi, semi-analytical models of the vibrating stiffened plates are developed in this paper. Approaches like the space harmonic method, Fourier transforms and finite element method （FEM） are adopted to investigate both kinds of the stiffened plates. In the present work, the vibro-acoustic responses of micro-perforated stiffened plates in the wavenumber space are expressed as functions of plate displacement amplitudes. After approximate numerical solutions of the amplitudes, the vibration equations and sound absorption coefficients of the two kinds of stiffened plates in the physical space are then derived by employing the Fourier inverse transform. In numerical examples, the effects of some physical parameters, such as the perforation ratio, incident angles and periodical distances etc., on the sound absorption performance are examined. The proposed approaches are also validated by comparing the present results with solutions of Takahashi and previous studies of stiffened plates. Numerical results indicate that the flexural vibration of the plate has a signif- icant effect on the sound absorption coefficient in the water but has little influence in the air.

关键词： Absorption- Stiffened- Micro-perforated Spaceharmonic - Finite element method

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Numerical evaluation of the shear stimulation effect in naturally fractured formations

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Science China Earth Sciences 2016年第2期59卷 371-383页

作者： wang yu LI Xiao ZHOU RunQing TANG ChunAn Key Laboratory of Shale Gas and Geoengineering Institute of Geology and Geophysics Chinese Academy of Sciences School of Civil and Hydraulic Engineering Dalian University of Technology

In shale gas fracking, the stimulated natural fracture system is often critical to the gas production. In this paper, we present the results of state-of-the-art modeling of a detailed parametric evolution of the shear stimulation effect in discrete fracture network(DFN) formations. Two-dimensional computational modeling studies have been used in an attempt towards understanding how naturally fractured reservoirs response in hydraulic fracturing. Simulations were conducted as a function of:(1) the in-situ stress ratio;(2) internal friction angle of DFN;(3) DFN orientation with the stress field; and(4) operational vari- ables such as injection rate. A sensitivity study reveals a number of interesting observations resulting from these parameters on the shear stimulation in natural fracture system. This work strongly links the production technology, geomechanical evaluation and aids in the understanding and optimization of hydraulic fracturing simulations in naturally fractured reservoirs.

关键词： Hydraulic fracturing DFN Numerical simulation Shear stimulation effect

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Neural Liénard system: learning periodic manipulation skills through dynamical systems

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Science China(Information Sciences) 2024年第12期67卷 256-271页

作者： Haoyu ZHANG Long CHENG yu ZHANG Yifan wang School of Artificial Intelligence University of Chinese Academy of Sciences State Key Laboratory for Multi-modal Artificial Intelligence Systems Institute of AutomationChinese Academy of Sciences

Learning from demonstrations provides effective methods for teaching robot manipulation ***, capturing periodic manipulation skills remains challenging with the current techniques. To address this gap, we introduce the neural Liénard system(neural LS), a novel neural network framework that utilizes Liénard-type differential equations to create dynamical systems with stable and distinct limit cycles. We also introduce an innovative technique, which not only manages periodic trajectories across various dimensions but also handles trajectories with intersections, enhancing the capability of the robot for complex tasks. We provide a thorough theoretical analysis of neural LS, focusing on its stability and representational *** evaluations show that neural LS achieves superior performance in modeling complex limit cycles,surpassing the existing methods. We particularly emphasize its effectiveness in handling high-dimensional periodic motions and trajectories with intersections. In addition, we explore the adaptability and robustness of neural LS. A practical application involving the Franka Emika robot in a drawing task further demonstrates the real-world utility of neural LS, confirming its effectiveness and potential to equip robots with advanced periodic manipulation skills.

关键词： learning from demonstrations stable dynamical system periodic motions

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Quasi-Static and Dynamic Collapse Behavior of Circular Foam-Filled Tubes Inspired by Bamboos

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Chinese Journal of Mechanical Engineering 2024年第6期37卷 235-257页

作者： Kai Liu Zhenhao yu Kaiyun wang Lin Jing State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China

The axial collapse mechanical behavior and energy absorption characteristics of circular foam-filled tubes mimicking the bamboo characteristics under quasi-static and low-velocity impact loads were investigated via experiments and numerical simulations in this *** crushing deformation process,load-displacement responses,the strain field and temperature field distribution characteristics of foam-filled tubes were *** energy absorption mechanism and crashworthiness performance of specimens were evaluated and compared with conventional empty tubes.E ects of ambient temperature on axial collapse behavior and crashworthiness indices were also *** results revealed that the superior energy absorption capacity of foam-filled tubes was attributed to the strengthening e ect of bionic joints and the filling e ect of aluminium *** energy absorption(EA),specific energy absorption(SEA),and other crashworthiness indices of foam-filled tubes under axial impact load were greatly improved than that of quasi-static *** to conventional empty tubes,the foam-filled tube had a larger energyabsorbing e ectiveness factor under both quasi-static and dynamic *** increased temperature weakens the crashworthiness performance and energy absorption ability of the foam-filled *** SEA values ranged from 28.2 J/g to 22.1 J/g for the quasi-static load and 31.9 J/g to 26.3 J/g for the dynamic load when the temperature elevated from-50℃to 100℃.

关键词： Foam-filled bionic tube Collapse behaviour Crashworthiness Energy absorption Dynamic load

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Experiments on and predictions about properties of sand bonded by microbe cement

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Science China(Technological Sciences) 2016年第8期59卷 1186-1193页

作者： QIAN ChunXiang RONG Hui yu XiaoNiu wang Xin School of Materials Science and Engineering Southeast University Nanjing 211189 China Research Institute of Green Construction Materials Southeast University Nanjing 211189 China

Microbe cement as a new bonding material is presented. Sandstone （0.05 m diameter, 0.5 m height） and sandpile （0.125 m^3） are joined by microbe cement to make a whole body. Evolutions in the related properties of treated sand samples are examined through compressive strength and calcite content. Results indicate that the structure of the cemented body is nonuniform, that the calcite content decreases with distance from the injection port, and that the compressive strength also decreases with dis- tance from the injection port. In addition, evolutions in the measured calcite content and compressive strength are summarized by a numerical model that considers microbe concentration distribution. The numerical results of the calcite content at different positions for 0.5 m height sandstone are similar to the test results, and the experimental results for calcite content and compres- sive strength of 0.125 m^3 cubic sandpile are similar to the numerical results. Prediction results indicate that the simulations should become a significant supplementary tool when microbe cement is applied in actual engineering projects.

关键词： microbe cement compressive strength calcite numerical model

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Limitation of spatial distribution of ammonia-oxidizing microorganisms in the Haihe River, China, by heavy metals

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Journal of Environmental Sciences 2014年第3期26卷 502-511页

作者： Chao wang Baoqing Shan Hong Zhang yu Zhao State Key Laboratory on Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences University of Chinese Academy of Sciences

The Haihe River is characterized by high ammonia pollution. Therefore, it is necessary to determine how environmental factors, such as heavy metals in the fiver limit the spatial distribution of ammonia-oxidizing microorganisms. In this study, the relationships between five heavy metals and ammonia-oxidizing microorganisms were studied. The results showed that under high ammonia, low oxygen and high concentrations of suspended particles, ammonia-oxidizing bacteria （AOB） ranged from 1013 to 104.8 gene copies/mL and ammonia-oxidizing archaea （AOA） ranged from 102.7 to 104.9 gene copies/mL. The average metal concentrations in water were 23.57 （Cr）, 21.58 （Ni）, 65.09 （Cu）, 622.03 （Zn） and 10.16 （As） Ixg/L, with those of Zn, Cu and Cr being higher than the US EPA criteria. Scatter plots of microbial abundance and metals indicated that both AOA and AOB were limited by heavy metals, but in different ways. As had an inhibitory effect on AOB, while Ni and Zn promoted AOA, and the other metals investigated showed no significant correlation with microbial abundance. Overall, our results indicated that the effects of heavy metals on ammonia-oxidizing microorganisms in water are complex, and that the final effect is determined by the physiological role of each element in the microorganisms, as well as environmental conditions such as complexation of organic matter, not simply the total metal concentration.

关键词： heavy metals AOA AOB Haihe River

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Deterministic learning-based neural output-feedback control for a class of nonlinear sampled-data systems

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Science China(Information Sciences) 2024年第9期67卷 164-183页

作者： yu ZENG Fukai ZHANG Tianrui CHEN Cong wang School of Automation Science and Engineering South China University of Technology School of Control Science and Engineering Shandong University

This study investigates the deterministic learning(DL)-based output-feedback neural control for a class of nonlinear sampled-data systems with prescribed performance(PP). Specifically, first, a sampleddata observer is employed to estimate the unavailable system states for the Euler discretization model of the transformed system dynamics. Then, based on the observations and backstepping method, a discrete neural network(NN) controller is constructed to ensure system stability and achieve the desired tracking performance. The noncausal problem encountered during the controller deduction process is resolved using a command filter. Moreover, the regression characteristics of the NN input signals are demonstrated with the observed states. This ensures that the radial basis function NN, based on DL theory, meets the partial persistent excitation condition. Subsequently, a class of discrete linear time-varying systems is proven to be exponentially stable, achieving partial convergence of neural weights to their optimal/actual values. Consequently, accurate modeling of unknown closed-loop dynamics is achieved along the system trajectory from the output-feedback control. Finally, a knowledge-based controller is developed using the modeling *** controller not only enhances the control performance but also ensures the PP of the tracking error. The effectiveness of the scheme is illustrated through simulation results.

关键词： deterministic learning neural networks adaptive neural control predefined performance nonlinear sampled-data systems

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通过氯化作用富集稀土精矿中钍和铈的研究

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稀有金属与硬质合金 2025年第1期53卷 18-25+39页

作者：王珂张丽奇张旭杨育圣赵增武内蒙古科技大学材料与冶金学院内蒙古工业大学材料科学与工程学院

通过MgCl2和AlCl3与稀土精矿的反应热力学计算、X射线衍射仪（XRD）和电感耦合等离子体原子发射光谱仪（ICP-AES）等，比较了MgCl2和AlCl3的氯化能力，测定了白云鄂博稀土精矿与MgCl2和AlCl3反应产物的物相组成和产物经过水浸后滤液中... 详细信息

通过MgCl2和AlCl3与稀土精矿的反应热力学计算、X射线衍射仪（XRD）和电感耦合等离子体原子发射光谱仪（ICP-AES）等，比较了MgCl2和AlCl3的氯化能力，测定了白云鄂博稀土精矿与MgCl2和AlCl3反应产物的物相组成和产物经过水浸后滤液中稀土和钍的含量，并研究了MgCl2和AlCl3对稀土氧化物(La2O3、CeO2、Nd2O3、Pr6O11等)和ThO2的氯化作用，以及对钍和铈的富集效果。结果表明，AlCl3对稀土精矿的氯化能力大于MgCl2,但反应产物中有氟化稀土和磷酸稀土形成，无法实现铈和钍的有效富集。利用焙烧-浸出法分离白云鄂博稀土精矿中稀土和钍的最佳条件为：稀土精矿中RE与MgCl2的物质的量之比1∶1.3、焙烧时间4 h、焙烧温度700℃、水浸时间1 h。在此条件下，钍的富集率达到82.5%,铈的富集率达到95.4%。

关键词：稀土精矿钍铈焙烧浸出氯化 MgCl2 AlCl3

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Hard carbon for sodium storage:Mechanism and performance optimization

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Nano Research 2024年第7期17卷 6038-6057页

作者： Yongxin wang Meng Li yu Zhang Naiqing Zhang State Key Laboratory of Urban Water Resource and Environment School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001China School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Due to the shortage of lithium resource reserves and the pressure of rising prices,sodium-ion batteries have regained the attention of the public,and shown great potential for application in the fields of grid energy storage and low-speed vehicles to achieve the purpose of complementing lithium-ion batteries,so it is imperative to promote the commercial application of sodiumion *** sodium-ion battery anode materials,hard carbon is the material most likely to be used ***,there is still much work to be done before its *** review provides a comprehensive overview of the current research status from the following three ***,the microstructure and sodium storage active sites of hard carbon are ***,the mechanism of sodium storage in hard carbon is investigated,which can be broadly categorized into four model,“insertion–filling”,“adsorption–insertion”,“adsorption–filling”,and“multistage”.Finally,from the perspective of improving the electrochemical performance of hard carbon,the performance improvement strategies proposed in recent years are *** with the performance of hard carbon commercial products of some enterprises,the future development goal of hard carbon is prospected,hoping that all sectors of society can work hard for this common goal.

关键词： sodium-ion battery hard carbon mechanism performance optimization

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