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An efficient method for collision-free and jerk-constrained trajectory generation with sparse desired way-points for a flying robot

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Science China(Technological Sciences) 2021年第8期64卷 1719-1731页

作者： CHEN YongXue DONG wei DING ye State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai200240China

In this paper,an efficient approach is developed to plan jerk-constrained smooth trajectories passing through desired way-points with allowable accuracy for an autonomous ***,based on the B-spline model,we introduce the sequential convex programming(SCP)into the flexible path planning method to satisfy the way-points *** approximating the quadrotor and obstacles as spheres and directed planes,the length-optimal and collision-free path planning problem is formulated as a nonconvex optimization problem and solved by *** initial C^(3) continuous path curve for optimization is constructed efficiently based on a proposed strategy of generating new way-points near the obstacles without the need to calculate the embedding distance between the curve and the *** this basis,the time-optimal speed planning problem is addressed in two *** the first step,the forward-backward approach is introduced to solve the problem under the chord error,velocity,and acceleration constraints by changing the variables and deforming the *** by relaxing the constraints appropriately,the problem under jerk constraints is formulated into a linear programming(LP)*** feasibility of the proposed approach is verified through simulations and an indoor navigation *** proposed approach can generate a C^(3) continuous collision-free trajectory that passes through the sparse desired way-points with allowable accuracy while guaranteeing the chord error,velocity,acceleration,and jerk *** the number of sample points is 3000,the proposed speed planning method reduces the calculation time by 40%compared to an existing method.

关键词： collision avoidance speed optimization motion planning sequential convex programming quadrotor

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Lane Departure Assistance Coordinated Control System for In-Wheel Motor Drive Vehicles Based on Dynamic Extension Boundary Decision

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Journal of Systems Science & Complexity 2020年第4期33卷 1040-1063页

作者： WANG Hongbo CUI wei ye Bin School of Automotive and Transportation Engineering Hefei University of TechnologyHefei 230009China Anhui Intelligent Vehicle Engineering Laboratory Hefei 230009China

Aiming at the advantages in active safety control of in-wheel motor drive vehicles, the classified decision-control-execution is proposed to the lane departure assistance system under the premise of ensuring the stability of the vehicle. The dynamic extension boundaries which vary with vehicle speed, road curvature and road adhesion coefficient are designed in the decision layer by using the neural network algorithm, which divides different dangerous degrees into different decision *** active differential steering controller, the electronic differential controller and their coordinated control strategy are designed in the control layer, and the corresponding control is carried out among different decision regions. In order to avoid the dangerous situation of secondary deviation caused by the existence of drift angle when the vehicle is rectified to the lane centerline, the heading angle controller is then designed in the control layer. The different torque distribution modes are divided according to the current vehicle speed, road adhesion coefficient and lateral acceleration in the execution layer, and the economic distribution, stability distribution, joint distribution are correspondingly executed among different torque distribution modes. Finally, Carsim and Matlab/Simulink are used for simulation verification.

关键词： execution Extension heading

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Efficiency of weak greedy algorithms for m-term approximations

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Science China Mathematics 2016年第4期59卷 697-714页

作者： ye PeiXin wei XiuJie School of Mathematical Sciences and LPMC Nankai University

We investigate the efficiency of weak greedy algorithms for m-term expansional approximation with respect to quasi-greedy bases in general Banach *** estimate the corresponding Lebesgue constants for the weak thresholding greedy algorithm（WTGA） and weak Chebyshev thresholding greedy *** we discuss the greedy approximation on some function *** some sparse classes induced by uniformly bounded quasi-greedy bases of L_p,12 the WCGA is better than the TGA.

关键词： m-term approximation Lebesgue constants weak thresholding greedy algorithm weak Chebyshev greedy algorithm quasi-greedy bases

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Inverse identification of the mechanical parameters of a pipeline hoop and analysis of the effect of preload

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Frontiers of Mechanical Engineering 2019年第3期14卷 358-368页

作者： ye GAO wei SUN School of Mechanical Engineering and Automation Northeastern University Shenyang 110819 China Key Laboratory of Vibration and Control of Aero-Propulsion Systems Ministry of Education of China Northeastern University Shenyang 110819 China

To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic load, must be obtained. In this study, an inverse method was developed by utilizing measured vibration data to identify the support stiffiiess and damping of a hoop. The procedure of identifying such parameters was described based on the measured natural frequencies and amplitudes of the frequency response functions (FRFs) of a pipeline system supported by two hoops. A dynamic model of the pipe-hoop system was built with the finite element method, and the formulas for solving the FRF of the pipeline system were provided. On the premise of selecting initial values reasonably, an inverse identification algorithm based on sensitivity analysis was proposed. A case study was performed, and the mechanical parameters of the hoop were identified using the proposed method. After introducing the identified values into the analysis model, the reliability of the identification results was validated by comparing the predicted and measured FRFs of the pipeline. Then, the developed method was used to identify the support stiffness and damping of the pipeline hoop under different preloads of the bolts. The influence of preload was also discussed. Results indicated that the support stiffiiess and damping of the hoop exhibited frequency-dependent characteristics. When the preloads of the bolts increased, the support stiffness increased, whereas the support damping decreased.

关键词： inverse identification pipeline hoop fiequency response function mechanical parameters preload

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A historical review of hybrid rice breeding

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Journal of Integrative Plant Biology 2024年第3期66卷 532-545页

作者： Xiaoming Zheng Fei wei Cheng Cheng qian qian State Key Laboratory of Crop Gene Resources and Breeding Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijing 100081China Yazhouwan National Laboratory Sanya City 572024China

The development of germplasm resources and advances in breeding methods have led to steady increases in yield and quality of rice (Oryza sativa L.). Three milestones in the recent history of rice breeding have contributed to these increases: dwarf rice breeding, hybrid rice breeding, and super rice breeding. On the 50th anniversary of the success of three-line hybrid rice,we highlight important scientific discoveries in rice breeding that were made by Chinese scientists and summarize the broader history of the field. We discuss the strategies that could be used in the future to optimize rice breeding further in the hope that China will continue to play a leading role in international rice breeding.

关键词： Chinese experience dwarf breeding hybrid rice breeding super rice breeding

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Sparse Reconstruction Method for DOA Estimation Based on Dynamic Dictionary and Negative Exponent Penalty

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Chinese Journal of Electronics 2018年第2期27卷 386-392页

作者： qian Tong CUI wei SHEN Qing School of Information and Electronic Beijing Institute of Technology

This paper proposes a novel sparse representation method for direction of arrival estimation based on dynamic dictionary and negative exponent penalty. The dynamic dictionary can eliminate the off-grid effect and the negative exponent penalty is capable of strengthening the sparse constraint to improve the performance. The basis is regarded as a part of the optimal target and the cross iteration is utilized to jointly update the dictionary and sparse support in this method. Based on the propositions of the penalty function, the penalty function is designed to replace of 1 norm because of its unbiasedness and stronger sparse constraint. The regularization parameter is simplified as a constant due to pre-white process, which greatly extends the application range of the proposed method. The simulation results show that the proposed method can efficiently reduce the off-grid effect and the over-complete rate of the original dictionary. Compared with the conventional sparse representation methods, it has better performance and lower computation complexity.

关键词： Direction of arrival(DOA) Sparse reconstruction Dynamic dictionary Penalty function

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Manifestation of acute peritonitis and pneumonedema in scrub typhus without eschar:A case report

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World Journal of Clinical Cases 2021年第23期9卷 6900-6906页

作者： Xiu-Ling Zhou Qing-Long ye Jia-qian Chen wei Li Hao-Jian Dong Department of Internal Medicine Guangdong Provincial People’s Hospital Zhuhai Hospital(Zhuhai Golden Bay Center Hospital)Zhuhai 519000Guangdong ProvinceChina

BACKGROUND Scrub typhus is an acute infectious disease caused by rickettsia *** diagnosis is based on eschar,and clinical manifestations can range from asymptomatic to multiorgan *** SUMMARY We report the case of a 35-year-old man living in Zhuhai,Guangdong,China,who had repeated high fever with a maximum body temperature of 40.2°C and elevated white blood cells and procalcitonin *** 7 d of persistent high fever,the patient developed rash,abdominal pain,and symptoms of *** 24 h after admission,the patient developed diffuse peritonitis and pneumonedema,requiring ventilator support in the intensive care ***,there was no eschar on the body,and the first weil-Felix test was *** into account that the patient had a history of jungle activities,doxycycline combined with meropenem was *** patient improved,healed,and was discharged after a *** diagnosis of scrub typhus was confirmed by a repeat weil-Felix test(Oxk 1:640),and pathology of the appendix resected by laparotomy suggests *** This rare presentation of peritonitis,pulmonary edema,and pancreatitis caused by scrub typhus reminds physicians to be alert to the possibility of scrub typhus.

关键词： Scrub typhus Peritonitis Pneumonedema Pancreatitis Myocarditis Vasculitis Case report

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Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

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Chinese Journal of Chemical Engineering 2019年第11期27卷 2675-2686页

作者： qian Liu Xianglan Zhang wei Li School of Chemical and Environmental Engineering China University of Mining and TechnologyBeijing 100083China School of Chemical Engineering Beijing Institute of Petro-Chemical TechnologyBeijing 102600China

Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids(ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents(COSMO-RS)model and the liquid–liquid phase equilibrium(LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and nheptane, 1-ethyl-3-methylimidazolium acetate(emim CH3 COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emim CH3 COO: model oils mass ratio of 0.5 and 298.15 K,emim CH3 COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.

关键词： Extraction M-cresol Ionic liquids Separation COSMO-RS Hydrogen bond

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Atomic origin of the traps in memristive interface

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Nano Research 2017年第6期10卷 1924-1931页

作者： ye Tian Lida Pan Chuan Fei Guo qian Liu CAS Center of Excellence for Nanoscience CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology No. 11 Beiyitiao Zhongguancun Beijing 100190 China School of Communication and Electronics Engineering Hunan City University Yiyang 413000 China Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 USA Institute of Physics Chinese Academy of Sciences Beijing 100190 China Photonics Research Group Department of Information Technology Ghent University-IMEC Ghent B-9000 Belgium Department of Materials Science and Engineering South University of Science and Technology of China Shenzhen 518055 China

In recent years, trap-related interfacial transport phenomena have received great attention owing to their potential applications in resistive switching devices and photo detectors. Not long ago, one new type of memristive interface that is composed of F-doped SnO2 and Bi2S3 nano-network layers has demonstrated a bivariate-continuous-tunable resistance with a swift response comparable to the one in neuron synapses and with a brain-like memorizing capability. However, the resistive mechanism is still not clearly understood because of lack of evidence, and the limited improvement in the development of the interfacial device. By combining I-V characterization, electron energy-loss spectroscopy, and first- principle calculation, we studied in detail the macro/micro features of the memristive interface using experimental and theoretical methods, and confirmed that its atomic origin is attributed to the traps induced by O-doping. This implies that impurity-doping might be an effective strategy for improving switching features and building new interfacial memristors.

关键词： memristance interface trap state first principle calculation

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Zircon U–Pb age and geochemical constraints on the origin and tectonic implication of the Tuotuohe Cenozoic alkaline magmatism in Qinghai–Tibet Plateau

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Acta Geochimica 2020年第1期39卷 67-84页

作者： ye qian Shengnan Tian Yujin Li Fengyue Sun College of Earth Sciences Jilin UniversityChangchunChina Key Laboratory of Mineral Resources Evaluation in Northeast Asia Ministry of Natural Resources of the People's Republic of ChinaChangchunChina

A large number of Eocene-Oligocene alkaline/alkali-rich igneous rocks were developed in the Tuotuohe region of the Qinghai-Tibetan *** this study,we present zircon U-Pb ages,Hf isotope data,and major and trace element compositions of the Cenozoic alkaline rocks from the Tuotuohe region in order to constraint the petrogenesis and tectonic evolution history of qiangtang *** U-Pb ages were measured via LA-ICP-MS to be39.6,37.6 and 32.0 *** 39.6 Ma trachyte was characterized by low SiO2 and high K2O and MgO *** 37.6 and 32.0 Ma orthophyres show enrichment in SiO2 and K2O,but deficient in *** of the samples belong to the alkaline *** rocks display enrichment in REE,LREE,and LILE,depletion in HFSE,and no obvious Eu *** and geochemical features suggest that there were two possible mechanisms for the origin of the alkaline rocks in the Tuotuohe region:(1)the removed mafic lower crust dropped into the asthenosphere,forming the mix magma(Nariniya trachyte);(2)the upwelling asthenosphere triggered the crustal melting(Nariniya and Zamaqu orthophyre).The Eocene-Oligocene alkaline rocks in the study and adjacent areas are likely to be the result of the same tectonic-magmatic event of deep lithospheric evolution that is the crustal material melting triggered by lithospheric *** conclusion extends the influence scope of lithospheric delamination eastward to the Tuotuohe region(*92°E)from Banda Co(*82°E).

关键词： Zircon U-Pb chronology Zircon Hf isotopic Delamination Tuotuohe region Qinghai–Tibetan Plateau

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