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Frontiers of Computer Science 2019年第5期13卷 1102-1115页

作者： Zhenxue HE limin XIAO fei gu li RUAN Zhisheng HUO Mingzhe li Mingfa ZHU Longbing ZHANG Rui liU Xiang WANG College of Information Science and Technology Hebei Agricultural University Baoding 071001 China State Key Laboratory of Software Development Environment Beihang University Beijing 100083 China School of Computer Science and Engineering Beihang University Beijing 100083 China School of Electronic and Information Engineering Beihang University Beijing 100083 China State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China National Engineering Research Center for Science & Technology Resources Sharing Service Beijing 100083 China

Delay optimization has recently attracted signif-icant attention. However, few studies have focused on the delay optimization of mixed-polarity Reed-Muller (MPRM) logic circuits. In this paper, we propose an efficient delay op-timization approach (EDOA) for MPRM logic circuits under the unit delay model, which can derive an optimal MPRM logic circuit with minimum delay. First, the simplest MPRM expression with the fewest number of product terms is ob-tained using a novel Reed-Muller expression simplification approach (RMESA) considering don't-care terms. Second, a minimum delay decomposition approach based on a Huffman tree construction algorithm is utilized on the simplest MPRM expression. Experimental results on MCNC benchmark cir-cuits demonstrate that compared to the Berkeley SIS 1.2 and ABC, the EDOA can significantly reduce delay for most cir-cuits. Furthermore, for a few circuits, while reducing delay, the EDOA incurs an area penalty.

关键词： delay optimization mixed-polarity Reed-Muller logic circuits unit delay model don't-care terms,

High Dynamic Bounding and Jumping Motion of Quadruped Robot Based on Stable Optimization Control

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Journal of Bionic Engineering 2024年第1期21卷 101-111页

作者： Sai gu fei Meng Botao liu Junyao Gao Qiang Huang School of Mechatronical Engineering Beijing Institute of Technology100081 BeijingChina Key Laboratory of Biomimetic Robots and Systems Ministry of EducationBeijing 100081China

Aiming at the environment such as ravines and obstacles that may be encountered in the actual movement,this paper proposes a method for optimizing the bounding and jumping motion based on the ground touching force trajectory and the air motion trajectory of the quadruped *** method of optimizing the ground reaction force according to the speed of the demand and the height of the jump,and adjusting the stance and swing time according to the relationship of dynamics and momentum *** the same time,under the constraints of dynamics and energy consumption of the robot system,considering the jumping distance and height,a method for optimizing the air trajectory of bounding and jumping is *** switching and landing stability control are also ***,the experimental results show that the quadruped robot has strong bounding and jumping ability,and has achieved stable bounding movement and forward jump movement of 0.8 m.

关键词： Quadruped robot High dynamic motion control-Periodic limit cycle Trajectory optimization

Time-domain Spectral Finite Element Method for Wave Propagation Analysis in Structures with Breathing Cracks

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Acta Mechanica Solida Sinica 2020年第6期33卷 812-822页

作者： Zexing Yu Chao Xu fei Du Shancheng Cao liaiigxian gu School of Astronautics Northwestern Polytechnic UniversityXVan 710072China

guided waves are generally considered as a powerful approach for crack detection in structures,which are commonly investigated using the finite element method(FEM).However,the traditional FEM has many disadvantages in solving wave propagation due to the strict requirement of mesh *** tackle this issue,this paper proposes an efficient time-domain spectral finite element method(SFEM)to analyze wave propagation in cracked structures,in which the breathing crack is modeled by definiiig the spectral gap ***,novel orthogonal polynomials and Gauss-Lobatto-Legendre quadrature rules are adopted to construct the spectral ***,a separable hard contact is utilized to simulate the breathing ***,a comparison of the numerical results between the FEM and the SFEM is conducted to demonstrate the high efficiency and accuracy of the proposed *** on the developed SFEM,the nonlinear features of waves and influence of the incident mode are also studied in detail,which provides a helpful guide for a physical understanding of the wave propagation behavior in structures with breathing cracks.

关键词： Time-domain spectral finite element method Contact nonlinearity Gap element Breathing crack

Optimal Reinsurance and Investment Strategies for Insurers with Regime-Switching and State-Dependent Utility Function

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Journal of Systems Science & Complexity 2016年第6期29卷 1658-1682页

作者： gu Ailing li Zhongfei School of Applied Mathematics Guangdong University of Technology Sun Yat-Sen Business School Sun Yat-Sen University

This paper considers a proportional reinsurance-investment problem and an excess-of-loss reinsurance-investment problem for an insurer,where price processes of the risky assets and wealth process of the insurer are both described by Markovian regime *** target of the insurer is assumed to maximize the expected exponential utility from her terminal wealth with a state-dependent utility *** employing the dynamic programming approach,the optimal value functions and the optimal reinsurance-investment strategies are *** addition,the impact of some parameters on the optimal strategies and the optimal value functions is analyzed,and lots of interesting results are discovered,such as the conclusion that excess-of-loss reinsurance is better than proportional reinsurance is not held in the regime-switching jump-diffusion model.

关键词： Excess-of-loss reinsurance optimal investment strategy proportional reinsurance regime-switching state-dependent utility function.

Adaptive dynamic surface control for air-breathing hypersonic vehicle

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Journal of Systems Engineering and Electronics 2013年第3期24卷 463-479页

作者： li Zhou Shumin fei School of Information and Control Nanjing University of Information Science and Technology School of Automation Southeast University

This paper describes an adaptive control approach for an air-breathing hypersonic vehicle. The control objective is to provide robust altitudes and velocity tracking in the presence of model uncertainties and varying disturbances. A fuzzy-neural disturbance observer is developed to estimate uncertainties and disturbances, and the adaptive controller is synthesized by the dynamic surface approach combing with the observer. The tracking error at the steady state can be guaranteed to converge to inside of a small residue set which the size of the set can be an arbitrary small value. Simulation results demonstrate the effectiveness of the presented approach.

关键词： flight control dynamic surface control fuzzy-neura system disturbance observer hypersonic vehicle.

Flow around three rectangular cylinders arranged in connected and separated Y-shape

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Acta Mechanica Sinica 2005年第4期21卷 336-341页

作者： Zhifu gu Yan li Department of Mechanics and Engineering Science Peking UniversityBeijing 100871 China

Characteristics of cross flow around three rectangular cylinders with two aspect ratios of breadth to width arranged in connected and separated Y-shape at various angles of incident flow were studied by means of force measurement in a wind tunnel. Flow visualizations with smoke-wire technique for typical cases were also given. Different types of flow patterns were formed for individual models at different angles of incident flow. From the results of fluctuating velocity measurement in the wake, features of vibration were determined. It shows that as the wind blows along the lines of one limb or rectangular cylinder of the model, oscillation is weak, whereas when the wind blows along the bisector lines of two limbs or cylinders, strong vibration is observed. It is associated with the regular vortex shedding.

关键词： Rectangular cylinders. Vortex-induced vibration Flow visualization Y-shape

A hybrid catalyst for efficient electrochemical N_(2)fixation formed by decorating amorphous MoS_(3)nanosheets with MIL-101(Fe)nanodots

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Science China Chemistry 2022年第5期65卷 885-891页

作者： Wan-Ying Xu Cong li fei-Long li Jiang-Yan Xue Wei Zhang Hongwei gu Brendan F.Abrahams Jian-Ping Lang College of Chemistry Chemical Engineering and Materials ScienceSoochow UniversitySuzhou 215123China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China School of Materials Engineering Changshu Institute of TechnologyChangshu 215500China School of Chemistry University of MelbourneVictoria 3010Australia

Metal-organic frameworks possessing relatively large pores,high surface areas,and unsaturated metal sites are attractive materials for use as electrocatalysts in the reduction of N_(2)to NH_(3).In this work,a MIL-101(Fe)/MoS_(3)hybrid catalyst,prepared by using a precursor-transformation strategy,is shown to be an effective electrocatalyst for the N_(2)reduction reaction(NRR).Under solvothermal conditions,micro-sized octahedral MIL-101(Fe)precursors are converted into ultra-small nanodots,while amorphous MoS_(3)derived from(NH_(4))_(2)MoS_(4)provides a surface suitable for anchoring the MIL-101(Fe)*** asprepared composite exhibits excellent electrocatalytic activity and durability for the NRR with a Faraday efficiency of 36.71%and an NH_(3)yield of 25.7μg h^(-1)mg_(cat)^(-1)at-0.1 V *** in 0.1 M *** results show that the dispersion and adherence of MIL-101(Fe)nanodots on amorphous MoS_(3)improves the exposure of active centers and aids mass transfer,resulting in greatly enhanced catalytic activity and stability.

关键词： nitrogen reduction reaction MIL-101(Fe)nanodots amorphous MoS_(3) precursor-transformation hybrid electrocatalysts

Probabilistic-constrained robust secure transmission for energy harvesting over MISO channels

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Science China(Information Sciences) 2018年第2期61卷 65-76页

作者： Bin li Zesong fei School of Information and Electronics Beijing Institute of Technology

In this paper, we consider a system supporting simultaneous wireless information and power transfer(SWIPT), where the transmitter delivers private message to a destination receiver(DR) and powers to multiple energy receivers(ERs) with multiple single-antenna external eavesdroppers(Eves). We study secure robust beamformer and power splitting(PS) design under imperfect channel state information(CSI).The artificial noise(AN) scheme is further utilized at the transmitter to provide strong wireless security. We aim at maximizing the energy harvested by ERs subject to the transmission power constraint, a range of outage constraints concerning the signal-to-interference-plus-noise ratio(SINR) recorded at the DR and the Eves, as well as concerning the energy harvested at the DR. The energy harvesting maximization(EHM)problem is challenging to directly solve, we resort to Bernstein-type inequality restriction technique to reformulate the original problem as a tractable approximated version. Numerical results show that our robust beamforming scheme outperforms the beamforming scheme relying on the worst-case design philosophy.

关键词： secure communication wireless power transfer power splitting Bernstein-type inequality robust beamforming

Operando HERFD-XANES and surface sensitive Δμ analyses identify the structural evolution of copper(Ⅱ) phthalocyanine for electroreduction of CO_(2)

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Journal of Energy Chemistry 2022年第1期31卷 1-7,I0001页

作者： Bingbao Mei Cong liu Ji li Songqi gu Xianlong Du Siyu Lu fei Song Weilin Xu Zheng Jiang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Electroanalytical Chemistry &Jilin Province Key Laboratory of Low Carbon Chemical PowerChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China College of Chemistry College of Materials Science and EngineeringZhengzhou UniversityZhengzhou 450000HenanChina Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China

The quantitative understanding of how atomic-level catalyst structural changes affect the reactivity of the electrochemical CO_(2)reduction reaction is *** to the complexity of catalytic systems,conventional in situ X-ray spectroscopy plays a limited role in tracing the underlying dynamic structural changes in catalysts active ***,operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy was used to precisely identify the dynamic structural transformation of well-defined active sites of a representative model copper(Ⅱ)phthalocyanine catalyst which is of guiding significance in studying single-atom catalysis *** X-ray spectroscopy analyses,including surface sensitive△μspectra which isolates the surface changes by subtracting the disturb of bulk base and X-ray absorption near-edge structure spectroscopy simulation,were used to discover that Cu species aggregated with increasing applied potential,which is responsible for the observed evolution of C_(2)H_(4).The approach developed in this work,characterizing the active-site geometry and dynamic structural change,is a novel and powerful technique to elucidate complex catalytic mechanisms and is expected to con tribute to the rational design of highly effective catalysts.

关键词： Operando HERFD-XANES △μanalysis Structural evolution Copper(Ⅱ)phthalocyanine Electrochemical CO_(2)reduction reaction

Growth Pattern and Its Indication of Spheroidal Nano-Micro Crystal Aggregates of Pyrite in the Baiyunpu Pb-Zn Polymetallic Deposit, Central Hunan

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Acta Geologica Sinica(English Edition) 2014年第6期88卷 1770-1783页

作者： GAO Shang HUANG fei gu Xiangping li Xiangyou MENG lin liU Rui SUN li GAO Wenyuan YU Huantao College of Resources and Civil Engineering Northeastern University School of Geosciences and Info-Physics Institute Central South University Yunxiang Mining limited Company

The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle Devonian, and its geological occurrence is consistent with the wall rocks. A large number of spheroidal pyrite aggregates are found unevenly distributed in the ores. The spheroidal aggregates are made up of kernels and concentric rings. The kernels are composed of approximately epigranular pyrite nanocrystals, while the rings are composed of accumulated pyrite microcrystals growing along the radial direction. The spheroidal pyrite aggregate and its outer zones can be divided into five areas（A–E）. The results of electron probe micro analysis（EPMA） show that from the zone A1 to B, Co/Ni 〈1, the sum of Co and Ni is 0.08%–0.26%, S/Fe increases from 2.06 to 2.15. While from the zone C to E, Ni cannot be detected and S/Fe decreases from 2.22 to 2.08. Powder X-ray diffraction（XRD） analysis in the micro zone shows obvious crystalline characteristics in the aggregates. Moving from the inside outwards, the maximum diffraction peak intensity of the（111） and（220） crystal planes of pyrite increases, and the crystallinity improves. The degree of change in the（111） plane is the most prominent. Considering the theory of crystal growth along with the geologic features of the depositional environment where the spheroidal pyrite aggregates developed, we confirm that the spheroidal aggregates are the result of nano-micro crystalline gathering and growth occurring by the following sequence of processes：nano-crystalline nucleation and growth, gathering into a ball, oriented growth of microcrystals, continuous accumulation, and adjustment of grain boundaries. The formation of the spheroidal pyrite aggregates in the late Qiziqiao Formation of the Middle Devonian occurred in a neutral to weak alkaline and reductive sedimentary environment in the normal oxygen-rich shallowwater

关键词： Baiyunpu Pb-Zn polymetallic deposit pyrite nano-micro crystal spheroidal aggregates growth pattern indication significance