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hierarchical policy with deep-reinforcement learning for nonprehensile multiobject rearrangement

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Biomimetic Intelligence & Robotics 2022年第3期2卷 1-8页

作者： Fan Bai fei Meng Jianbang Liu Jiankun Wang Max q-h.Meng Department of Electronic Engineering The Chinese University of Hong KongShatin N.T.Hong Kong SARChina Department of Electronic and Electrical Engineering Southern University of Science and TechnologyShenzhenChina Shenzhen Research Institute of the Chinese University of hong Kong ShenzhenChina

Nonprehensile multiobject rearrangement is the robotic task of planning feasible paths and transferring multiple objects to their predefined target poses without *** must consider how each object reaches the target and the order in which objects move,considerably increasing the complexity of the ***,we propose a hierarchical policy for nonprehensile multiobject rearrangement based on deep-reinforcement *** use imitation learning and reinforcement learning to train a rollout *** a high-level policy,the policy network directs the Monte Carlo tree search algorithm to efficiently seek the ideal rearrangement sequence for several *** a low-level policy,the robot plans the paths according to the order of path primitives and manipulates the objects to approach the target poses one by *** experiments show that the proposed method has a higher success rate,fewer steps,and shorter path length than the state-of-the-art methods.

关键词： Rearrangement Reinforcement learning Monte Carlotreesearch

Relevant Region sampling strategy with adaptive heuristic for asymptotically optimal path planning

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Biomimetic Intelligence & Robotics 2023年第3期3卷 21-29页

作者： Chenming Li fei Meng han Ma Jiankun Wang Max q-h.Meng Department of Electronic Engineering The Chinese University of Hong KongHong Kong 999077China Department of Electronic and Electrical Engineering Southern University of Science and TechnologyShenzhen 518055China Shenzhen Research Institute of the Chinese University of hong Kong Shenzhen 518057China

Sampling-based planning algorithm is a powerful tool for solving planning problems in highdimensional state *** this article,we present a novel approach to sampling in the most promising regions,which significantly reduces planning *** RRT#algorithm defines the Relevant Region based on the cost-to-come provided by the optimal forward-searching ***,it uses the cumulative cost of a direct connection between the current state and the goal state as the *** improve the path planning efficiency,we propose a batch sampling method that samples in a refined Relevant Region with a direct sampling strategy,which is defined according to the optimal cost-to-come and the adaptive cost-to-go,taking advantage of various sources of heuristic *** proposed sampling approach allows the algorithm to build the search tree in the direction of the most promising area,resulting in a superior initial solution quality and reducing the overall computation time compared to related *** validate the effectiveness of our method,we conducted several simulations in both SE(2)and SE(3)state *** the simulation results demonstrate the superiorities of proposed algorithm.

关键词： Path planning Asymptotical optimality Relevant Region Adaptive heuristic

Rational design of AgGaS/ZnS/ZnS quantum dots with a near-unity photoluminescence quantum yield via double shelling scheme

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Journal of Materials Science & Technology 2024年第2期169卷 235-242页

作者： h.X.lu h.Liu Z.Z.Fu Y.Y.Chen h.q.Dai Z.hu W.L.Zhang R.q.Guo Institute for Electric Light Sources School of Information Science and TechnologyFudan UniversityShanghai 200433China Institute of Future Lighting Academy for Engineering and TechnologyFudan UniversityShanghai 200433China Yiwu Research Institute of Fudan University YiwuZhejiang 322000China Zhongshan-Fudan Joint Innovation Center Zhongshan 528437China

In this study,a two-step method was used to synthesize highly luminescent AgGaS/ZnS/ZnS quantum dots(qDs).In the first step,an inner ZnS shell was formed via a one-pot method,which resulted in a smaller lattice mismatch between the AgGaS core and the outer ZnS shell,thereby facilitating the formation of a thick outer *** the two-step shelling process,the synthesized AgGaS/ZnS/ZnS qDs showed an excellent photoluminescence quantum yield(PLqY)of 96.4%with a peak wavelength of 508 nm,repre-senting the highest PLqY reported thus far for AgGaS ***,the effect of halogen ions in Zn precursors on the shelling process was *** was proposed that the capacity of halogen ions to coordinate with the qDs influenced the balance between Zn cation diffusion and ZnS shelling ***,the ZnS shelling reaction was dominant when ZnCl_(2)was employed,while Zn cation diffusion was the dominant process under the I^(−)-rich *** work provides insights into the interfacial restructuring during the ZnS shelling and offers a clear map for the tailored synthesis of core/shell qDs.

关键词： AgGaS quantum dots Photoluminescence Core/shell Alloyed core/shell interface

Review on hydrogen Embrittlement of Press-hardened Steels for Automotive Applications

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1123-1143页

作者： Z.Wang q.lu Z.h.Cao h.Chen M.X.huang J.F.Wang General Motors China Science Lab Shanghai201206China Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong Kong999077China Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Press-hardened steel(PhS)with an ultimate tensile strength(UTS)of 1500 MPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achieved by hot stamping ***,the application of PhS with UTS exceeding 1500 MPa in automotive industry could be deferred due to the increased risk of hydrogen *** reduce this kind of risk,recent research efforts have been focused on various ways to optimize the microstructure of *** present review intends to summarize these efforts,to highlight present solutions to address hydrogen embrittlement,and to shed light on directions for future *** influence of microstructure on the hydrogen embrittlement of PhS has been discussed in terms of both the steel substrate and the surface *** substrate part covers the influence of martensite,carbides,inclusions,and retained austenite,while the surface part covers decarburization and oxidation,pre-coating,and trimming.

关键词： hot stamping Press-hardened steels Coating-free hydrogen embrittlement Fracture Al-Si coating

Flexural-gravity wave resistances due to a surface-moving line source on a fluid covered by a thin elastic plate

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Theoretical & Applied Mechanics Letters 2013年第2期3卷 68-71页

作者： D.q.lu h.Zhang Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

Analytical solutions for the flexural-gravity wave resistances due to a line source steadily moving on the surface of an infinitely deep fluid are investigated within the framework of the linear po- tential theory. The homogenous fluid, covered by a thin elastic plate, is assumed to be incompressible and inviscid, and the motion to be irrotational. The solution in integral form for the wave resistance is obtained by means of the Fourier transform and the explicitly analytical solutions are derived with the aid of the residue theorem. The dispersion relation shows that there is a minimal phase speed cmin, a threshold for the existence of the wave resistance. No wave is generated when the moving speed of the source V is less than emin while the wave resistances firstly increase to their peak values and then decrease when V ~〉 Crnin. The effects of the flexural rigidity and the inertia of the plate are studied. @ 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi：10.1063/2.1302202]

关键词： wave resistance hydroelasticity flexural rigidity inertia

Stabilization of Cu/ZnO Based Catalysts by Nickel Additive in Methanol Decomposition

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Chemical Research in Chinese Universities 2001年第4期17卷 420-425页

作者： XI Jing-yu WANG Zhi-fei lu Gong-xuan State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical PhysicsThe Chinese Academy of SciencesLanzhou 730000P.R.China

A series of Cu/Zn based catalysts with and without Ni, prepared by the co-precipitation method, has been studied for methanol decomposition. CO and h2 are the major products. The Cu/Zn catalysts show a low initial activity and a poor stability. The formation of the CuZn alloys was observed in the deactivated Cu/Zn catalysts which were used for methanol decomposition at 250 . When small amounts of Ni were added in the catalyst, the Cu/Zn/Ni(molar ratio 5/4/ x) catalysts showed a high activity at a low temperature. The activity and the stability of the catalyst depend on the nickel content. The activity of the Cu/Zn/Ni catalysts was maintained at a. relatively stable value of 78% conversion of methanol with 95% selectivity of h2, 93% selectivity of CO, and a more than 70% yield of hydrogen was obtained at 250 C when x >1. The stability of the Cu/Zn/Ni (molar ratio 5/4/x) catalysts showed the maximum (ca 88%) when x=1. The stabilization effect of nickel on the Cu/Zn based catalysts may lead to the increasing of the dispersion of active Cu species and the prevention of CuZn alloys formation.

关键词： Nickel Cu/Zn catalysts Stabilization Methanol Decomposition

Soil Microbial Activities in Beech Forests Under Natural Incubation Conditions as Affected by Global Warming

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Pedosphere 2014年第6期24卷 709-721页

作者： S.lu q.WANG S.KATAhATA M.NARAMOTO h.MIZUNAGA Graduate School of Science and Technology Shizuoka University Graduate School of Agriculture Shizuoka University

Microbial activity in soil is known to be controlled by various factors. however, the operating mechanisms have not yet been clearly identified, particularly under climate change conditions, although they are crucial for understanding carbon dynamics in terrestrial ecosystems. In this study, a natural incubation experiment was carried out using intact soil cores transferred from high altitude(1 500 m) to low(900 m) altitude to mimic climate change scenarios in a typical cold-temperate mountainous area in Japan. Soil microbial activities, indicated by substrate-induced respiration(SIR) and metabolic quotient(q CO2), together with soil physicalchemical properties(abiotic factors) and soil functional enzyme and microbial properties(biotic factors), were investigated throughout the growing season in 2013. Results of principal component analysis(PCA) indicated that soil microbial biomass carbon(MBC) andβ-glucosidase activity were the most important factors characterizing the responses of soil microbes to global warming. Although there was a statistical difference of 2.82 ℃ between the two altitudes, such variations in soil physical-chemical properties did not show any remarkable effect on soil microbial activities, suggesting that they might indirectly impact carbon dynamics through biotic factors such as soil functional enzymes. It was also found that the biotic factors mainly controlled soil microbial activities at elevated temperature,which might trigger the inner soil dynamics to respond to the changing environment. Future studies should hence take more biotic variables into account for accurately projecting the responses of soil metabolic activities to climate change.

关键词： biotic factors carbon dynamics metabolic quotient microbial biomass soil enzymes soil respiration

Effect of isotope on state-to-state dynamics for reactive collision reactions O(3P)+h2^+→Oh^++h and O(3P)+h2^+→Oh+h^+ in ground state 1^2A" and first excited 1^2A' potential energy surfaces

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Chinese Physics B 2020年第2期29卷 231-242页

作者： Juan Zhao Ting Xu lu-lu Zhang Li-fei Wang School of Science Shandong Jiaotong UniversityJinan 250357China School of Physics and Electronics Shandong Normal UniversityJinan 250358China

We carry out quantum scattering dynamics and quasi-classical trajectory（qCT） calculations for the O+h2+ reactive collision in the ground（12 A"）.nd first excited（12 A’） potential energy *** calculate the reaction probabilities of O+h2+（v=0,j=0）→Oh++h and O+h2+（v=0,j=0）→Oh+h+reaction for total angular momentum J=*** results calculated by qCT are consistent with those from quantum mechanical wave *** the qCT method,we generate in the center-of-mass frame the product state-resolved integral cross-sections（ICSs）;two commonly used generalized polarization-dependent differential cross-sections（PDDCS s）,（2π/σ）(dσ00/dωt),（2π/σ）(dσ20/dωt));and three angular distributions of the product rotational vectors,p（θr）,P（φr）,and p（θr,φr）.We discuss the influence on the scalar and vector properties of the potential energy surface,the collision energy,and the isotope *** there are deep potential wells in these two potential energy surfaces,their kinetic characteristics are similar to each other and the isotopic effect is not ***,the well depths and configurations of the two potential energy surfaces are different,so the effects of isotopic substitution on the integral cross-section and the rotational polarization of product are different.

关键词： quasi-classical trajectory state-to-state isotopic substitution rotational polarization of product

A mechanism for enhanced photocatalytic activity of nano-size silver particle modified titanium dioxide thin films

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Science China(Technological Sciences) 2010年第11期53卷 3027-3032页

作者： MENG FanMing lu fei SUN Zhaoqi LüJianGuo School of Physics and Materials Science Anhui UniversityHefei 230039China Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Dalian University of Technology)Ministry of EducationDalian 116024China Anhui Key Laboratory of Information Materials and Devices Anhui UniversityHefei 230039China Department of Physics and Electronic Engineering Hefei Normal UniversityHefei 230061China

Ag-TiO2 nanostructured thin films with silver volume fraction of 0–20% were deposited on silicon and quartz substrates by RF magnetron sputtering and annealed in ambient air at 950°C for 1 h. The phase structure and surface topography of the films were characterized by X-ray diffractometer and transmission electron microscope. Photocatalytic activity of the films was evaluated by light induced degradation of methyl orange (C14h14N3NaO3S) solution using a high pressure mercury lamp as lamp-house. The relation of photocatalytic activity and silver content was studied in detail. It was found that silver content influences phase structure of TiO2 thin films, and silver in the films is metallic Ag (Ag0). With increasing silver content from 0 to 20 vol%, photocatalytic activity of the films increases first and then decreases. A suitable amount (2.5–5 vol%) silver addition can significantly enhance the photocatalytic activity of TiO2 films. The enhanced photocatalytic activity was mainly attributed to the extension of visible light absorption region of the films, the presence of anatase phase, the increase of oxy-gen anion radicals O2? and reactive center of surface Ti3+, and the better separation between electrons and holes on the films surface.

关键词： silver nanoparticle TiO2 thin film photocatalytic activity RF magnetron sputtering methyl orange