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General closed-form inverse kinematics for arbitrary three-joint subproblems based on the product of exponential model

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Frontiers of Mechanical Engineering 2022年第2期17卷 85-101页

作者： Tao SONG bo PAN Guojun niu Jiawen YAN Yili FU State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China

The inverse kinematics problems of robots are usually decomposed into several Paden–Kahan subproblems based on the product of exponential model. However, the simple combination of subproblems cannot solve all the inverse kinematics problems, and there is no common approach to solve arbitrary three-joint subproblems in an arbitrary postural relationship. The novel algebraic geometric (NAG) methods that obtain the general closed-form inverse kinematics for all types of three-joint subproblems are presented in this paper. The geometric and algebraic constraints are used as the conditions precedent to solve the inverse kinematics of three-joint subproblems. The NAG methods can be applied in the inverse kinematics of three-joint subproblems in an arbitrary postural relationship. The inverse kinematics simulations of all three-joint subproblems are implemented, and simulation results indicating that the inverse solutions are consistent with the given joint angles validate the general closed-form inverse kinematics. Huaque III minimally invasive surgical robot is used as the experimental platform for the simulation, and a master–slave tracking experiment is conducted to verify the NAG methods. The simulation result shows the inverse solutions and six sets given joint angles are consistent. Additionally, the mean and maximum of the master–slave tracking experiment for the closed-form solution are 0.1486 and 0.4777 mm, respectively, while the mean and maximum of the master–slave tracking experiment for the compensation method are 0.3188 and 0.6394 mm, respectively. The experiments results demonstrate that the closed-form solution is superior to the compensation method. The results verify the proposed general closed-form inverse kinematics based on the NAG methods.

关键词： inverse kinematics Paden-Kahan subproblems three-joint subproblems product of exponential closed-form solution

Solution of Center-Focus Problem for a Class of Cubic Systems

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Chinese Annals of Mathematics,Series B 2016年第1期37卷 149-160页

作者： bo SANG Chuanze niu School of Mathematical Sciences Liaocheng University

For a class of cubic systems, the authors give a representation of the n th order Liapunov constant through a chain of pseudo-divisions. As an application, the center problem and the isochronous center problem of a particular system are considered. They show that the system has a center at the origin if and only if the first seven Liapunov constants vanish, and cannot have an isochronous center at the origin.

关键词：三次系统焦点问题 Liapunov 求解中心问题李雅普诺夫常数等时

Master event based backazimuth estimation and its application to downhole microseismic monitoring

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Petroleum Science 2022年第6期19卷 2675-2682页

作者： Xiao-bo Meng Hai-Chao Chen Feng-Lin niu Yi-Jing Du Department of Geophysics Chengdu University of TechnologyChengduSichuan610059China Unconventional Petroleum Research Institute and State Key Laboratory of Petroleum Resources and ProspectingChina University of PetroleumBeijing102249China Department of Earth Environmental and Planetary SciencesRice UniversityHoustonTX77005USA Petro China Research Institute of Petroleum Exploration and Development Beijing100083China

Microseismic monitoring provides a valuable tool for evaluating the effectiveness of hydraulic fracturing operations.However,robust detection and accurate location of microseismic events are challenging due to the low signal to noise ratio(SNR)of their signals on seismograms.In a downhole monitoring setting,P-wave polarization direction measured from 3-component records is usually considered as the backazimuth of the microseismic event,i.e.,the direction of the event.The direction and arrival time difference between the P and S waves is used to locate the seismic event.When SNR is low,an accurate estimate of event backazimuth becomes very challenging with the traditional covariance matrix method.Here we propose to employ a master event and use a grid search method to find the backazimuth of a target event that maximizes the dot product of the two backazimuthal vectors of the master and target events.We compared the backazimuths measured with the proposed grid-search and the conventional covariance-matrix methods using a large synthetic dataset.We found that the grid-search method yields more accurate backazimuth estimates from low SNR records when measurements are made at single geophone level.When array data are combined,the proposed method also has some advantage over the covariance-matrix method,especially when the number of geophones is low.We also applied the method to a microseismic dataset acquired by a hydraulic fracturing project at a shale play site in southwestern China and found that the relocated microseismic events tend to align along existing faults more tightly than those in the original catalog.

关键词： Hydraulic fracturing Microseismic event Back azimuth Master event Grid search Covariance-matrix

Inhomogeneous strain and doping of transferred CVD-grown graphene

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Rare Metals 2022年第5期41卷 1727-1734页

作者： Yu-Ting niu Fang-Zhu Qing Xue-Song Li bo Peng National Engineering Research Center of Electromagnetic Radiation Control Materials University of Electronic Science and Technology of ChinaChengdu 611731China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 611731China School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Shenzhen Institute for Advanced Study University of Electronic Science and Technology of ChinaShenzhen 518110China

Chemical vapor deposition(CVD)-grown graphene on copper foils is subject to the Cu substrate, which affects the spatial distribution of strain and doping, thus influencing the electronic properties of graphene. However, plenty of electronic devices based on CVD-grown graphene require transfer process and the distribution of doping and strain in CVD-grown graphene transferred onto the insulating substrates remains elusive.

关键词： graphene transferred strain

Recycling Spent LiCoO_(2)Battery as a High-efficient Lithiumdoped Graphitic Carbon Nitride/Co_(3)O_(4)Composite Photocatalyst and Its Synergistic Photocatalytic Mechanism

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Energy & Environmental Materials 2023年第2期6卷 45-53页

作者： bo niu Jiefeng Xiao Zhenming Xu School of Environmental Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The ever-increasing quantity of spent lithium-ion batteries(LIBs)is both a potential environmental pollutant and a valuable resource.The spent LIBs recycling mainly aimed at the separation of valuable elements.Some issues still exist in these processes such as high energy consumption and complex separation procedures.This study avoided element separation and proposed a facile approach to transform spent LiCoO_(2) electrode into a lithium(Li)-doped graphitic carbon nitride(g-C_(3)N_(4))/Co_(3)O_(4) composite photocatalyst through one-pot in situ thermal reduction.During the thermal process,melamine served as the reductant for LiCoO_(2) decomposition and the raw material for g-C_(3)N_(4) production.Li was in situ doped in g-C_(3)N_(4) and the generated Co_(3)O_(4) was in situ integrated,forming a Li-doped g-C_(3)N_(4)/Co_(3)O_(4) composite photocatalyst.This special composite exhibited an enhanced photocatalytic performance,and its photocatalytic H2 production and RhB degradation rates were 8.7 and 6.8 times higher than those of g-C_(3)N_(4).The experiments combined with DFT calculation revealed that such enhanced photocatalytic efficiency was ascribed to the synergy effect of Li doping and Co_(3)O_(4) integrating,which extended the visible light absorption(450-900 nm)and facilitated the charge transfer and separation.This study transforms waste into a high-efficient catalyst,realizing high-valued utilization of waste and environmental protection.

关键词： composite photocatalyst environmental protection spent LIBs synergy mechanism waste utilization

MiR-19a-3p/PTEN axis regulates the anticancer effect of circHIAT1in breast cancer in vitro

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BIOCELL 2023年第10期47卷 2301-2312页

作者： CHAO niu RUOFEI SUN XIAOGANG LI bo LI XIAODONG HE Department of General Surgery Lanzhou University Second HospitalLanzhou730000China Department of General Surgery Affiliated Hospital of Yunnan UniversityKunming650051China

Objective: Breast cancer is a major cancer threatening the health of women globally. To elucidate the effect ofthe circHIAT1/miR-19a-3p/phosphatase and tensin homolog (PTEN) axis on regulating the malignant phenotype ofbreast cancer cells. Methods: The mRNA expression pattern of circHIAT1, miR-19a-3p, and PTEN was checked byreal-time quantitative polymerase chain reaction. Then, the knockdown assay was carried out to explore the effect ofcircHIAT1 and miR-19a-3p on breast cancer. The relative cell experiments, including MTT assay, scratch assay,transwell invasion assay, and flow cytometry analysis, were conducted to verify the influence of circHIAT1 and miR-19a-3p on breast cancer cells. Results: The levels of PTEN and circHIAT1 were reduced, while that of miR-19a-3pwas elevated in breast cancer tissues and cells. MiR-19a-3p was proved to be the target gene of circHIAT1 via a dualluciferase experiment, which could also modulate the PTEN mRNA level. Overexpression of circHIAT1 was able toundermine the growth, migratory ability, and invasiveness in breast cancer cells, which could be antagonized by miR-19a-3p mimic. The inhibition of miR-19a-3p in vitro also impaired the malignancy of breast cancer, which dependedon the modulation of PTEN expression. Conclusion: CircHIAT1 controls the PTEN expression level in cells of breastcancer by negatively regulating miR-19a-3p. This mechanism controls the growth, invasion, and migration of breastcancer.

关键词： CircRNA CicrHIAT1 MiR-19a-3p PTEN Breast cancer

Exploring the tidal effect of urban business district with large-scale human mobility data

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Frontiers of Computer Science 2023年第3期17卷 77-90页

作者： Hongting niu Ying SUN Hengshu ZHU Cong GENG Jiuchun YANG Hui XIONG bo LANG School of Computer Science and Engineering Beihang UniversityBeijing 100191China Key Lab of Intelligent Information Processing of Chinese Academy of Sciences(CAS) Institute of Computing TechnologyCASBeijing 100086China Baidu Talent Intelligence Center Baidu Inc.Beijing 100085China Business School Imperial College LondonLondon SW72AZUK Artificial Intelligence Thrust The Hong Kong University of Science and TechnologyGuangzhou 510030China

Business districts are urban areas that have various functions for gathering people,such as work,consumption,leisure and entertainment.Due to the dynamic nature of business activities,there exists significant tidal effect on the boundary and functionality of business districts.Indeed,effectively analyzing the tidal patterns of business districts can benefit the economic and social development of a city.However,with the implicit and complex nature of business district evolution,it is non-trivial for existing works to support the fine-grained and timely analysis on the tidal effect of business districts.To this end,we propose a data-driven and multi-dimensional framework for dynamic business district analysis.Specifically,we use the large-scale human trajectory data in urban areas to dynamically detect and forecast the boundary changes of business districts in different time periods.Then,we detect and forecast the functional changes in business districts.Experimental results on real-world trajectory data clearly demonstrate the effectiveness of our framework on detecting and predicting the boundary and functionality change of business districts.Moreover,the analysis on practical business districts shows that our method can discover meaningful patterns and provide interesting insights into the dynamics of business districts.For example,the major functions of business districts will significantly change in different time periods in a day and the rate and magnitude of boundaries varies with the functional distribution of business districts.

关键词： business district trajectory functionality detection tidal effect boundary detection visiting score

Electro-oxidation of Ni(Ⅱ)-citrate complexes at BDD electrode and simultaneous recovery of metallic nickel by electrodeposition

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Journal of Environmental Sciences 2022年第6期34卷 103-113页

作者： Qiongfang Zhuo Xiaofeng Xu Shuibo Xie Xiuwen Ren Zhongying Chen bo Yang Yanliang Li Junfeng niu School of Civil Engineering University of South ChinaHengyang 421001China School of Environment and Civil Engineering Dongguan University of TechnologyDongguan 523808China South China Institute of Environmental Sciences MEEGuangzhou 510655China College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518071China

The simultaneous electro-oxidation of Ni(Ⅱ)-citrate and electrodeposition recovery of nickel metal were attempted in a combined electro-oxidation-electrodeposition reactor with a boron-doped diamond(BDD)anode and a polished titanium cathode.Effects of initial nickel citrate concentration,current density,initial p H,electrode spacing,electrolyte type,and initial electrolyte dosage on electrochemical performance were examined.The efficiencies of Ni(Ⅱ)-citrate removal and nickel metal recovery were determined to be 100%and over 72%,respectively,under the optimized conditions(10 m A/cm^(2),pH 4.09,80 mmol/L Na_(2)SO_(4),initial Ni(Ⅱ)-citrate concentration of 75 mg/L,electrode spacing of 1 cm,and 180 min of electrolysis).Energy consumption increased with increased current density,and the energy consumption was 0.032 kWh/L at a current density of 10 m A/cm^(2)(pH 6.58).The deposits at the cathode were characterized by scanning electron microscopy(SEM),energy-dispersive spectrometry(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).These characterization results indicated that the purity of metallic nickel in cathodic deposition was over 95%.The electrochemical system exhibited a prospective approach to oxidize metal complexes and recover metallic nickel.

关键词： Electrochemical oxidation Electrodeposition BDD anode Metal complexes Metallic nickel recovery

An ion-released MgI_(2)-doped separator inducing a LiI-containing solid electrolyte interphase for dendrite-free Li metal anodes

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Journal of Energy Chemistry 2022年第12期75卷 83-94,I0003页

作者： Shan Yi Zhe Su Wanyu Zhang Hongli Chen Yayun Zhang bo niu Donghui Long State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Key Laboratory for Specially Functional Materials and Related Technology of the Ministry of Education East China University of Science and TechnologyShanghai 200237China

Lithium metal batteries are among the strong contenders to satisfy the ever-increasing needs of energy storage systems,which however suffer from poor composition of the solid electrolyte interphase(SEI)layer and uncontrolled Li dendrites formation.In this regard,we report on the design of an ionreleased MgI_(2)-doped polyacrylonitrile(PAN)based nanofiber(MPANF)separator,which can lead to conducive SEI layer and dendrite-free Li anode.The combination of the lithophilic MgI_(2)nanoparticles with polarized PAN matrix comprehensively functions as a high-compatible interpenetrating network to homogenize ionic transportation and confront dendrite growth.The released I ions introduce the highion-conductivity LiI into SEI layer,which could induce the formation of favorable and protective interface layer in the early stage,as embodied in the enrichment of advantageous components such as LiN_(x)O_(y),Li_(2)O,LiF,and Li_(3)N.Profited from the high-affinity MPANF separator,the Li||Li symmetric cell achieves an ultralow voltage hysteresis of 46 mV with an extended lifespan of 580 h.And a prolonged lifetime of 590cycles with an enhanced specific capacity of 140.1 m Ah g^(-1)and the Coulombic efficiency of 96.2%at 1C can be obtained in full cells.This work may offer a facile and high-affinity alternative to traditional polymeric separators for high-performance and dendrite-free Li metal batteries.

关键词： Lithium metal anode LiI-containing layer Dendrite-free anode Electrospun nanofiber separator