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Dynamic motion of quadrupedal robots on challenging terrain:a kinodynamic optimization approach

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Frontiers of Mechanical Engineering 2024年第3期19卷 23-40页

作者： qi LI lei DING Xin LUO Engineering Research Center of Hubei Province for Clothing Information Wuhan 430200China school of Computer science and Artificial Intelligence Wuhan Textile UniversityWuhan 430200China state Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

The dynamic motion of quadrupedal robots on challenging terrain generally requires elaborate spatial–temporal kinodynamic motion planning and accurate control at higher refresh rate in comparison with regular ***,conventional quadrupedal robots usually generate relatively coarse planning and employ motion replanning or reactive strategies to handle terrain *** resultant complex and computation-intensive controller may lead to nonoptimal motions or the breaking of locomotion *** this paper,a kinodynamic optimization approach is *** generate long-horizon optimal predictions of the kinematic and dynamic behavior of the quadruped robot on challenging terrain,we formulate motion planning as an optimization problem;jointly treat the foot’s locations,contact forces,and torso motions as decision variables;combine smooth motion and minimal energy consumption as the objective function;and explicitly represent feasible foothold region and friction constraints based on terrain *** track the generated motions accurately and stably,we employ a whole-body controller to compute reference position and velocity commands,which are fed forward to joint controllers of the robot’s *** verify the effectiveness of the developed approach through simulation and on a physical quadruped robot *** show that the quadruped robot can successfully traverse a 30°slope and 43% of nominal leg length high step while maintaining the rhythm of dynamic trot gait.

关键词： quadrupedal robot kinodynamic planning nonlinear optimization challenging terrain whole-body control

Improved Double Deep Q Network-Based Task scheduling Algorithm in Edge Computing for Makespan Optimization

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Tsinghua science and Technology 2024年第3期29卷 806-817页

作者： lei Zeng qi Liu shigen shen Xiaodong Liu school of Computer science Nanjing University of Information Science and TechnologyNanjing 210044China school of software Nanjing University of Information Science and TechnologyNanjing 210044China school of Information Engineering Huzhou UniversityHuzhou 313000China school of Computing Edinburgh Napier UniversityEdinburghEH105DTUK

Edge computing nodes undertake an increasing number of tasks with the rise of business ***,how to efficiently allocate large-scale and dynamic workloads to edge computing resources has become a critical *** study proposes an edge task scheduling approach based on an improved Double Deep Q Network(DQN),which is adopted to separate the calculations of target Q values and the selection of the action in two networks.A new reward function is designed,and a control unit is added to the experience replay unit of the *** management of experience data are also modified to fully utilize its value and improve learning *** learning agents usually learn from an ignorant state,which is *** such,this study proposes a novel particle swarm optimization algorithm with an improved fitness function,which can generate optimal solutions for task *** optimized solutions are provided for the agent to pre-train network parameters to obtain a better cognition *** proposed algorithm is compared with six other methods in simulation *** show that the proposed algorithm outperforms other benchmark methods regarding makespan.

关键词： edge computing task scheduling reinforcement learning makespan Double Deep Q Network(DQN)

Degradation analysis and doping modification optimization for high-voltage P-type layered cathode in sodium-ion batteries

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Journal of Energy Chemistry 2024年第2期89卷 1-9,I0002页

作者： Bao Zhang Yi Zhao Minghuang Li qi Wang lei Cheng lei Ming Xing Ou Xiaowei Wang National Engineering Laboratory for High-Efficiency Recovery of Refractory Nonferrous Metals School of Metallurgy and EnvironmentCentral South UniversityChangsha 410083HunanChina Zhejiang Power New Energy Co. LTDZhuji 311800ZhejiangChina

Advancing high-voltage stability of layered sodium-ion oxides represents a pivotal avenue for their progress in energy storage *** this,a comprehensive understanding of the mechanisms underpinning their structural deterioration at elevated voltages remains insufficiently *** this study,we unveil a layer delamination phenomenon of Na_(0.67)Ni_(0.3)Mn_(0.7)O_(2)(NNM)within the 2.0-4.3 V voltage,attributed to considerable volumetric fluctuations along the c-axis and lattice oxygen reactions induced by the simultaneous Ni^(3+)/Ni^(4+)and anion redox *** introducing Mg doping to diminished Ni-O antibonding,the anion oxidation-reduction reactions are effectively mitigated,and the structural integrity of the P2 phase remains firmly intact,safeguarding active sites and precluding the formation of novel *** Na_(0.67)Mg_(0.05)Ni_(0.25)Mn_(0.7)O_(2)(NMNM-5)exhibits a specific capacity of100.7 mA h g^(-1),signifying an 83%improvement compared to the NNM material within the voltage of2.0-4.3 *** investigation underscores the intricate interplay between high-voltage stability and structural degradation mechanisms in layered sodium-ion oxides.

关键词： soidum ion batteries Layer cathode materials P-type High-voltage performance Degradation analysis

Roof collapse mechanism of weak surrounding rock for deep-buried tunnels under high geostress conditions

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Journal of Mountain science 2024年第7期21卷 2408-2426页

作者： ZHANG qi GUO Xiaokang YAN Zhiguo lei Zhongdai sHEN Yixin school of Civil Engineering Southeast UniversityNanjing 211189China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

High geostress,a typical attribute of tunnels located at significant depths,is crucial in causing stress-induced failure and influencing the stability of the tunnel *** study developed an analytical method for the failure mechanism that occurs in deep-buried tunnel roofs,taking into account the influence of *** limit analysis theory was utilized for deriving analytical solutions about the geometry of the collapsing surface and the limit supporting *** collapsing surface obtained by the analytical solution was validated by the findings of the physical model test,which shows a high level of agreement with the actual *** extensive investigation was done to explore the effects of the lateral pressure coefficients,the tunnel buried depth,the geological conditions of the surrounding rock,the long-short axis ratio,and the size of the tunnel *** findings indicate that an increase in the lateral pressure coefficient from 0.5 to 1.5 results in a reduction in the height of the collapsing zone by 2.08 m and the width of the collapsing zone by 1.15 m,while simultaneously increases the limit supporting pressure by 18.9%.The proposed upper bound method accurately determines the limit supporting pressure and the geometry of the collapsing surface,which aligns well with the results acquired through numerical modelling and on-site monitoring in actual engineering *** proposed analytical method can serve as a reference for similar crown failure issues of deep-buried tunnels.

关键词： Geostress Deep-buried tunnels Collapse mechanism Pressure arch Limit analysis HoekBrown criterion

Hollow Metal-Organic Framework/MXene/Nanocellulose Composite Films for Giga/Terahertz Electromagnetic shielding and Photothermal Conversion

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Nano-Micro Letters 2024年第9期16卷 161-179页

作者： Tian Mai lei Chen Pei‑Lin Wang qi Liu Ming‑Guo Ma Research Center of Biomass Clean Utilization MOE Engineering Research Center of Forestry Biomass Materials and BioenergyBeijing Key Laboratory of Lignocellulosic ChemistryCollege of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083People’s Republic of China state silica-Based Materials Laboratory of Anhui Province Bengbu 233000People’s Republic of China

With the continuous advancement of communication technology,the escalating demand for electromagnetic shielding interference(EMI)materials with multifunctional and wideband EMI performance has become *** the electrical and magnetic components and designing the EMI material structure have attracted extensive interest,but remain a huge ***,we reported the alternating electromagnetic structure composite films composed of hollow metal-organic frameworks/layered MXene/nanocellulose(HMN)by alternating vacuum-assisted filtration *** HMN composite films exhibit excellent EMI shielding effectiveness performance in the GHz frequency(66.8 dB at Kaband)and THz frequency(114.6 dB at 0.1-4.0 THz).Besides,the HMN composite films also exhibit a high reflection loss of 39.7 dB at 0.7 THz with an effective absorption bandwidth up to 2.1 ***,HMN composite films show remarkable photothermal conversion performance,which can reach 104.6℃under 2.0 sun and 235.4℃under 0.8 W cm^(−2),*** unique micro-and macrostructural design structures will absorb more incident electromagnetic waves via interfacial polarization/multiple scattering and produce more heat energy via the local surface plasmon resonance *** features make the HMN composite film a promising candidate for advanced EMI devices for future 6G communication and the protection of electronic equipment in cold environments.

关键词： Metal-organic frameworks MXene Nanocellulose Electromagnetic shielding Photothermal conversion

Fabrication and characterization of multi-scale coated boron powders with improved combustion performance:A brief review

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Defence Technology（防务技术） 2024年第1期31卷 27-40页

作者： Rui Liu Danfeng Yang Kunyu Xiong Ying-lei Wang qi-Long Yan science and Technology on Combustion Internal Flow and Thermo-structure LaboratoryNorthwestern Polytechnical UniversityXi'an710072China Xi'an Modern Chemistry Research Institute Xi'an710065China

Boron has high mass and volume calorific values,but it is difficult to ignite and has low combustion *** literature review summarizes the strategies that are used to solve the above-mentioned problems,which include coatings of boron by using fluoride compounds,energetic composites,metal fuels,and metal *** techniques include recrystallization,dual-solvent,phase transfer,electrospinning,*** one of the effective coating agents,the fluorine compounds can react with the oxide shell of boron *** comparison,the energetic composites can effectively improve the flame temperature of boron powder and enhance the evaporation efficiency of oxide film as a condensed *** and metal oxides would react with boron powder to form metal borides with a lower ignition point,which could reduce its ignition temperature.

关键词： Boron powder coating structure and morphology Condensed phase thermal reaction Ignition and combustion

Highly Differentiated Target Detection under Extremely Low-Light Conditions Based on Improved YOLOX Model

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Computer Modeling in Engineering & sciences 2024年第8期140卷 1507-1537页

作者： Haijian shao s.qin lei Chenxu Yan Xing Deng Yunsong qi school of Computer Jiangsu University of Science and TechnologyZhenjiang212003China Department of Electrical and Computer Engineering University of NevadaLas VegasNV89154USA Zhejiang Geely Automobile Research Institute Ningbo315336China

This paper expounds upon a novel target detection methodology distinguished by its elevated discriminatory efficacy,specifically tailored for environments characterized by markedly low luminance *** methodologies struggle with the challenges posed by luminosity fluctuations,especially in settings characterized by diminished radiance,further exacerbated by the utilization of suboptimal imaging *** envisioned approach mandates a departure from the conventional YOLOX model,which exhibits inadequacies in mitigating these *** enhance the efficacy of this approach in low-light conditions,the dehazing algorithm undergoes refinement,effecting a discerning regulation of the transmission rate at the pixel level,reducing it to values below 0.5,thereby resulting in an augmentation of image ***,the coiflet wavelet transform is employed to discern and isolate high-discriminatory attributes by dismantling low-frequency image attributes and extracting high-frequency attributes across divergent *** utilization of CycleGAN serves to elevate the features of low-light imagery across an array of stylistic *** computational methodologies are then employed to amalgamate and conflate intricate attributes originating from images characterized by distinct stylistic orientations,thereby augmenting the model’s erudition *** validation conducted on the PAsCAL VOC and Ms COCO 2017 datasets substantiates pronounced *** refined low-light enhancement algorithm yields a discernible 5.9%augmentation in the target detection evaluation index when compared to the original *** Average Precision(mAP)undergoes enhancements of 9.45%and 0.052%in low-light visual renditions relative to conventional YOLOX *** envisaged approach presents a myriad of advantages over prevailing benchmark methodologies in the realm of target detection within environments marked by an acute scarcity of lumi

关键词： Target detection extremely low-light wavelet transformation highly differentiated features YOLOX

Molecular engineering binuclear copper catalysts for selective CO_(2) reduction to C_(2) products

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Journal of Energy Chemistry 2024年第6期93卷 166-173,I0005页

作者： qi Zhao Kai lei Bao Yu Xia Rachel Crespo-Otero Devis Di Tommaso Department of Chemistry School of Physical and Chemical SciencesQueen Mary University of LondonLondonE14NSUK Key Laboratory of Material Chemistry for Energy Conversion and storage(Ministry of Education) Hubei Key Laboratory of Material Chemistry and Service FailureState Key Laboratory of Materials Processing and Die&Mould TechnologySchool of Chemistry and Chemical EngineeringHuazhong University of Science and Technology(HUST)Wuhan 430074HubeiChina Department of Chemistry University College LondonLondonWC1H 0AJUK Digital Environment Research Institute Queen Mary University of LondonEmpire HouseLondon E11HHUK

Molecular copper catalysts serve as exemplary models for correlating the structure-reaction-mechanism relationship in the electrochemical CO_(2) reduction(eCO_(2)R),owing to their adaptable environments surrounding the copper metal *** investigation,employing density functional theory calculations,focuses on a novel family of binuclear Cu molecular *** modulation of their coordination configuration through the introduction of organic groups aims to assess their efficacy in converting CO_(2) to C_(2)*** findings highlight the crucial role of chemical valence state in shaping the characteristics of binuclear Cu catalysts,consequently influencing the eCO_(2)R behaviour,Notably,the Cu(Ⅱ)Cu(Ⅱ)macrocycle catalyst exhibits enhanced suppression of the hydrogen evolution reaction(HER),facilitating proton trans fer and the eCO_(2)R *** rthermore,we explo re the impact of diverse electro n-withdrawing and electron-donating groups coordinated to the macrocycle(R=-F,-H,and-OCH_3)on the electron distribution in the molecular *** placement of-OCH_3 groups in the macrocycles leads to a favourable oxidation state of the Cu centres and subsequent C-C coupling to form C_(2) *** research provides fundamental insights into the design and optimization of binuclear Cu molecular catalysts for the electrochemical conversion of CO_(2) to value-added C_(2) products.

关键词： Molecular catalyst design selective CO_(2)reduction C_(2)products Density functional theory calculations

Research progress on semi-continuous casting of magnesium alloys under external field

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China Foundry 2024年第5期21卷 516-524页

作者： qi-yu Liao qi-chi Le Da-zhi Zhao lei Bao Tong Wang Yong-hui Jia Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China school of Materials science and Engineering Northeastern UniversityShenyang 110819China Key Laboratory of Lightweight structural Materials Liaoning ProvinceNortheastern UniversityShenyang 110819China Key Laboratory of Light-weight Materials Nanjing Tech UniversityNanjing 210009China

High-performance magnesium alloys are moving towards a trend of being produced on a large scale and in an integrated *** foundational key to their successful production is the high-quality cast *** alloys produced through the conventional semi-continuous casting process inevitably contain casting defects,which makes it challenging to manufacture high-quality *** integration of external field assisted controlled solidification technology,which combines physical fields such as electromagnetic and ultrasonic fields with traditional semi-continuous casting processes,enables the production of high-quality magnesium alloy ingots characterized by a homogeneous microstructure and absence of *** article mainly summarizes the technical principles of those external field assisted casting *** focus is on elaborating the refinement mechanism of different types of electromagnetic fields,ultrasonic fields,and combined physical fields during the solidification of magnesium ***,the development prospects of producing highquality magnesium alloy ingots through semi-continuous casting under the external field were discussed.

关键词： semi-continuous casting electromagnetic field ultrasonic field magnesium alloys refinement mechanism